2023 - on this day in the past . . .

On this day in 1801 – January 1st – Giuseppe Piazzi discovered Ceres.

Ceres was the first object discovered in what's now known as the asteroid belt. It was at first considered a planet, then an asteroid, and is now classed as a dwarf planet.

On this day in 1925 – January 1st – Edwin Hubble read to the American Astronomical Society what would be a ground-breaking paper.

Hubble showed that the Andromeda "nebula" wasn't an object in the Milky Way, but a galaxy in its own right. Here is picture of the glass plate on which Hubble discovered a Cepheid variable - marked VAR! - in the Andromeda galaxy. From this he determined that it was too far away to be located in our own galaxy.

On this day in 2019 – January 1st – NASA's New Horizons spacecraft made a fly-by of 486958 Arrokoth.

Arrokoth is a trans-Neptunian object located in the Kuiper belt. It's the farthest and most primitive object in the Solar System to be visited by a spacecraft.

On this day in 1871 – January 2nd – American astronomer Anne Sewell Young was born in Bloomington, Wisconsin.

In 1899 she went to teach at Mount Holyoke College where she was appointed director of the John Payson Williston Observatory. She remained there until her retirement. Young's primary astronomical interest was in variable stars. She was one of the eight original members of the American Association of Variable Star Observers (AAVSO).

On this day in 1920 – January 2nd – American author and scientist Isaac Asimov was born in Petrovichi, Soviet Russia.

(The exact date of Asimov's birth was unknown due to the state of record-keeping, but he always celebrated on January 2nd.) Asimov was a professor of chemistry, and also a prolific writer on many subjects. He's best remembered for his works of science fiction and of popular science, including astronomy.

On this day in 1959 – January 2nd – the Soviet Union's Luna 1 was the first spacecraft to leave the Earth's gravitational field.

Luna 1 passed to within 6000 km of the Moon, and ended up in orbit around the Sun.

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On this day in 2004 – January 3rd – NASA's rover Spirit landed on Mars.

Along with the Opportunity rover, the rovers' missions were designed to last for just over three months. Spirit was active until 2010.
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On this day in 1643 – January 4th – Isaac Newton was born in Woolsthorpe Manor in Woolsthorpe-by-Colsterworth, near Grantham, Lincolnshire, England.

The great physicist and mathematician was born on Christmas Day 1642, according to the Julian Calendar then in use. Nearly a century later England adopted the Gregorian calendar, and the equivalent date is ten days later.
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On this day in 1797 – January 4th – German amateur astronomer Wilhelm Beer was born in Berlin.

Beer, along with Johannes Heinrich Maedler, published the first map of the Moon (Mappa Salenographica). They also made a map of Mars and calculated the planet's rotation period to within 0.1 second of today's figure.
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On this day in 1892 – January 5th – the first successful photograph was taken of an aurora.

Early cameras couldn't catch the dim light of an aurora, and long exposures didn't capture the movement. German physicist Martin Brendel and a fellow scientist, on an expedition in northern Norway, took the first successful image, and revolutionized the study of the northern lights.
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On this day in 2005 – January 5th – astronomers Michael E. Brown, Chadwick A. Trujillo and David L. Rabinowitz discovered Eris.

Eris is a trans-Neptunian object orbiting the Sun once every 557 years at an average distance of 1.7 times that of Pluto. It's slightly smaller than Pluto, but more massive, and was thought to be a 10th planet. But Eris and Pluto were finally defined as dwarf planets by the International Astronomical Union.
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On this day in 1998 – January 6th – NASA's Lunar Prospector was launched.

The mission was designed to investigate the Moon from low polar orbit. This would include mapping the surface composition, locating lunar resources, and measuring magnetic and gravity fields.
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On this day in 1610 – January 7th – Galileo wrote the first letter in which he described his observations of the Moon through a telescope.

In Galileo's time, the Moon was thought to be a perfectly smooth sphere. However Galileo saw that the surface was uneven with mountains, plains and valleys.
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On this day in 1610 – January 7th – Galileo first saw three of Jupiter's moons.

The three objects he saw in his telescope are now known as Callisto, Io and Europa, three of the four Galilean moons.
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On this day in 1587 – January 8th – Johannes Fabricius was born in Resterhafe, East Friesland (now part of Germany).

Fabricius was a Frisian/German astronomer, eldest son of David Fabricius who was also an astronomer. In their solar observing, they discovered sunspots about the same time as, and independently of, Galileo.
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On this day in 1942 – January 8th – English theoretical physicist Stephen Hawking was born in Oxford, England. The 80th anniversary of his birth was celebrated by Google.

For thirty years he was the Lucasian Professor at the University of Cambridge, a prestigious post once held by Isaac Newton. Hawking also wrote books on cosmology for the general public, the best known being A Brief History of Time. He was most closely associated with his work on black holes.
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On this day in 1839 – January 9th – Thomas Henderson published his determination of the distance to Alpha Centauri.

Henderson had actually been the first person to calculate the distance to a fixed star by using stellar parallax. However he had delayed publishing his results, and the credit for being first went elsewhere.
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On this day in 1992 – January 9th – Aleksander Wolszczan and Dale Frail announced the discovery of two planets orbiting the millisecond pulsar PSR 1257+12.

They had discovered the first exoplanets, i.e., planets outside our Solar System. Later, Wolszczan discovered a third planet in the system.
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On this day in 1946 – January 10th – the US Army Signal Corps had the first successful echo detection of a radar signal bounced off the Moon.

It was part of the first experiment in radar astronomy, a technique used decades later to map the planet Venus.
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On this day in 1787 – January 11th – William Herschel discovered the Uranian moons Oberon and Titania.

It would be almost five decades after Titania and Oberon were discovered that another astronomer would observe them.
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On this day in 1873 – January 11th – American lawyer and amateur astronomer William Tyler Olcott was born in Chicago, Illinois.

As well as founding the American Association of Variable Star Observers (AAVSO), Olcott wrote a number of popular books on astronomy.
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On this day in 1907 – January 12th – Sergei Pavlovich Korolev was born in Zhytomyr, Ukraine.

Korolev was the mastermind of the Soviet space program, and a state secret. If he was referred to at all, it was as the Chief Designer, not by name.
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On this day in 1610 – January 13th – Galileo discovered a fourth satellite of Jupiter.

This was the moon we now know as Ganymede, the biggest moon in the Solar System.
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On this day in 1916 – January 14th – the Royal Astronomical Society in London, founded in 1820, finally admitted the first elected female Fellows.

Recognising their achievement in astronomy and geophysics, Mary Adele Blagg, Ella K Church, A Grace Cook and Fiammetta Wilson were admitted to full membership in the society.
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On this day in 2005 – January 14th – the European Space Agency (ESA) probe Huygens landed on Saturn's moon Titan.

It was the first time a spacecraft had been landed on a moon other than our own. Here is footage of the Huygens landing on Titan.
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On this day in 2008 – January 14th – NASA's MESSENGER spacecraft made its first flyby of Mercury.

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) was the second spacecraft to reach Mercury, the first having been Mariner 10 in 1975.
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On this day in 2006 – January 15th – NASA's Stardust spacecraft completed its mission by returning its samples to Earth.

Stardust was a robotic space probe whose primary mission was to collect dust samples from the coma of comet Wild 2, as well as samples of cosmic dust.
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On this day in 1969 – January 16th – the first docking of two manned spacecraft occurred.

The Soviet Soyuz 4 and Soyuz 5 docked in space and transferred crew from one vehicle to another by a space walk.
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On this day in 2015 – January 16th – the UK Space Agency announced that the remains of the probe Beagle 2 had been located on Mars.

The probe had been lost on Christmas Day 2003 after successful insertion into orbit by Mars Express. It was finally identified in images from the HiRise camera on the Mars Reconnaissance Orbiter (MRO).
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On this day in 1647 – January 17th – Elisabetha Hevelius (née Koopmann), the second wife of Johannes Hevelius, was born in Gdańsk, Poland.

She is considered to be one of the first European female astronomers, and is often called 'The mother of Moon charts'. Elisabetha helped her husband manage his observatory, and published two of his works after his death.
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On this day in 2002 – January 18th – Gemini South Observatory was dedicated.

Gemini South in Chile and Gemini North in Hawaii together constitute the Gemini Observatory. The twin telescopes provide almost complete coverage of the skies with two of the largest and most advanced optical/infrared telescopes available.
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On this day in 1747 – January 19th – Johann Bode was born in Hamburg, Germany.

Bode was the director of the Berlin Observatory for nearly forty years. In 1801 he published his influential star atlas Uranographia. A keen popularizer of astronomy, he also produced a smaller atlas aimed at amateur astronomers. His name also lives on in the "Titius-Bode Law".
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On this day in 1851– January 19th – Dutch astronomer Jacobus Kapteyn was born in Barneveld, Netherlands.

Kapteyn was best known for his studies of the Milky Way. He was the first to discover evidence that galaxies rotate.
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On this day in 2006– January 19th – NASA's New Horizons spacecraft was launched.

The spacecraft made a flyby of the Plutonian system in the summer of 2015, and on New Year's Day 2019, followed it up with a flyby of the Kuiper Belt object informally called Ultima Thule, but later renamed Arrokoth.
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On this day in 1573 – January 20th – German astronomer Simon Marius was born in Gunzenhausen, Germany.

Marius claimed he had seen Jupiter's moons before Galileo. Galileo's documentation was more extensive and published first, so he got the credit. However, the suggestions Marius made for naming the four large moons were eventually adopted.
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On this day in 1930 – January 20th – Edwin "Buzz" Aldrin was born in Glen Ridge, New Jersey.

The second man to step onto the Moon has been not only an astronaut, but also an Air Force combat pilot, aerial gunnery instructor and flight commander. His doctoral thesis at MIT was on techniques for manned orbital rendezvous.
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On this day in 2014 – January 20th – ESA's Rosetta spacecraft awoke from a deep space hibernation of over thirty months.

Rosetta's historic mission saw her then catch up with a comet, go into orbit around it, put a lander on its surface, and follow the comet as it went around the Sun.
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On this day in 1908 – January 21st – Danish astronomer and astrophysicist Bengt Strömgren was born in Gothenburg, Sweden.

He applied quantum mechanics to understanding stars, produced pioneering work in the chemical composition of stars, and discovered vast shells of ionized hydrogen around stars, now known as Strömgren Spheres.
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On this day in 1592 – January 22nd – Pierre Gassendi was born in Champtercier, France.

He was a French philosopher, priest, astronomer, and scientific observer, experimentalist and chronicler. Gassendi was also the first person ever to see a planet transiting the Sun when he observed the 1631 transit of Mercury.
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On this day in 2003 – January 22nd – the last signal from Pioneer 10 was received.

Pioneer 10 was the first spacecraft to pass through the asteroid belt, and later the first to pass the orbit of Pluto. Originally designed for a 21-month mission, it functioned for more than 30 years. It's now reckoned to be about 132 AU from the Earth, headed in the direction of Taurus. (One AU is the distance from the Earth to the Sun.)
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On this day in 1986 – January 24th – Voyager 2 flew past Uranus.

This fly-by was the first and only visit of a spacecraft to the ice giant Uranus.
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On this day in 1736 – January 25th – French-Italian mathematician Joseph Lagrange was born in Turin, Italy.

Lagrange was one of the great minds of the 18th century, and his work included major contributions to physics and astronomy. He's best known now for his identification of equilibrium points between the gravity of the Earth and that the Sun. NASA's SOHO (Solar and Heliospheric Observatory) sits at one of these points, and the James Webb Space Telescope at another.
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On this day in 1983 – January 25th – the Infrared Astronomical Satellite (IRAS) was launched.

IRAS, a joint project of NASA (USA), NIVR (Netherlands) and SERC (UK), was the first space telescope to carry out a survey of the whole night sky at infrared wavelengths.
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On this day in 1994 – January 25th – Clementine was launched.

Over a period of nearly four months, the US spacecraft Clementine made scientific observations of the Moon. In addition, the craft was used to test the effects on sensors and components of extended exposure to space.
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On this day in 2004 – January 25th – the Mars rover Opportunity landed on the red planet.

The mission was designed to last 90 Martian days, but it was operational until the summer of 2018 when an exceptionally severe dust storm blanketed Mars for three months. The rover didn't recover from the loss of power, and the mission was officially brought to an end in February 2019.
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On this day in 1978 – January 26th – the International Ultraviolet Explorer (IUE) was launched.

The IUE was a joint effort by the European Space Agency (ESA), the UK Science Research Council and NASA. It was switched off in 1996, after it had worked 14 years beyond its planned lifetime.
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On this day in 1829 – January 27th – pioneering astrophotographer Isaac Roberts was born in Groes Bach, Henllan, Denbighshire, Wales, UK.

Roberts was an amateur astronomer and a fellow of the Royal Geological Society. He developed a photographic technique which made it possible to capture faint objects. Roberts's photograph of the Andromeda Nebula actually showed the spiral structure of M31.
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On this day in 1941 – January 27th – New Zealand astrophysicist Beatrice Hill Tinsley was born in Chester, England.

Beatrice Tinsley began her career late, and died in 1981, but in the intervening years she revolutionized our view of galactic evolution. Her pioneering work continues to be regularly cited by researchers.
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On this day in 1967 – January 27th – the crew of Apollo 1, Virgil "Gus" Grissom, Edward White and Roger Chaffee, died when fire swept through the command module during a preflight test.

They are commemorated at the Astronaut Memorial at the Kennedy Space Center in Florida.
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On this day in 1611 – January 28th – Polish astronomer Johannes Hevelius was born in Danzig (Gdańsk), Poland.

Johannes Hevelius studied sunspots, produced a lunar chart, discovered several comets, and compiled an important star atlas. He was one of the most influential astronomers of the 17th century.
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On this day in 1611 – January 28th – NASA's space shuttle Challenger was engulfed in a huge fireball soon after launch. The seven crew members perished in the accident.

They are commemorated at the Astronaut Memorial at the Kennedy Space Center in Florida.
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On this day in 1935 – January 29th – Czech astronomer Luboš Kohoutek was born in Zábřeh, Czechia.

Kohoutek has discovered over 70 minor planets, a number of planetary nebulae, a supernova and several comets. His name is probably best known internationally from the periodic comets that bear his name.
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On this day in 1958– January 31st – the United States launched Explorer 1.

The first satellite launched by the United States, it was part of the U.S. participation in the International Geophysical Year. It was the first spacecraft to detect the Van Allen radiation belt.
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On this day in 2003 – February 1st – NASA's space shuttle Columbia broke up during re-entry, killing the seven crew members.

They are commemorated at the Astronaut Memorial at the Kennedy Space Center in Florida.
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On this day in 1966 – February 3rd – the Soviet spacecraft Luna 9 made the first successful soft landing on the Moon.

Luna 9 also sent back the first pictures taken on the Moon's surface.
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On this day in 1995 – February 3rd – Eileen Collins became the first woman to pilot a space shuttle, flying Discovery to the Russian Mir space station.

Four years later she would became the first woman commander of a space shuttle.
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On this day in 1906 – February 4th – Clyde Tombaugh was born in Streator, Illinois.

Tombaugh was the American astronomer who discovered Pluto. He died in 1997, and a portion of his ashes were on the New Horizons spacecraft that journeyed to Pluto and beyond.
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On this day in 1963 – February 5th – Dutch astronomer Maarten Schmidt had a sudden insight that provided the clue to solving the mystery of quasars.

Schmidt realized that a quasar wasn't an object in our Galaxy, and its strange spectrum wasn't full of unknown elements. It was mostly composed of hydrogen that was redshifted because of its enormous distance away in an expanding Universe.
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On this day in 1974 – February 5th – NASA's Mariner 10 took a historic gravity assist from Venus in order to make its flyby of Mercury.

It was the first spacecraft to turn the theoretical possibility of such a gravity assist into a reality, and it enabled the first visit of a spacecraft to Mercury.
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On this day in 1971– February 6th – Alan Shepard hit the first golf balls on the Moon.

The Apollo 14 lunar module landed on the Moon on February 5th with lunar module pilot Ed Mitchell and commander Alan Shepard. Shepard hit the golf balls on their second exploration of the Moon. (Note: Shepard also hit the last golf balls on the Moon. So far!)
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On this day in 1824 – February 7th – English astronomer and pioneering spectroscopist, William Huggins, was born in London.

He is best remembered for revolutionizing observational astronomy through the application of spectroscopic methods to determine the chemical constituents of stars and other celestial objects.
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On this day in 1984 – February 7th – On this day in 1984 – February 7th – during space shuttle mission STS-41B, NASA astronaut Bruce McCandless made the first untethered spacewalk.
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On this day in 1999 – February 7th – NASA's Stardust comet probe was launched.

Stardust was the first sample return mission to collect samples of cosmic dust, and of dust from a comet's coma, then return them to Earth.
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On this day in 1826 – February 8th – Jules Verne was born in Nantes, France.

The French author was a major European literary figure, best known in the English-speaking world for his exciting and influential adventure stories, many of which are considered early science fiction. Ray Bradbury said "We are all, in one way or another, the children of Jules Verne."
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On this day in 1974 – February 8th – the last crew to occupy NASA's Skylab returned to Earth.

Skylab, the first US space station, was launched in May 1973.
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On this day in 1960 – February 9th – biochemist and NASA astronaut, Peggy Whitson, was born in Mount Ayr, Iowa, USA.

Whitson was the first woman to command the International Space Station, and she did it twice. She was also NASA's Chief Astronaut and although now retired, still has the record for the most time in space of any NASA astronaut.
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On this day in 2021 – February 9th – the Hope orbiter of the United Arab Emirates was inserted into Mars orbit.

The mission was designed to study the Martian atmosphere and climate.
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On this day in 2021 – February 10th – the Chinese Tienwen-1 orbiter was inserted into Martian orbit.

In addition to an orbiter, the mission included a lander and a rover.
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On this day in 2010 – February 11th – NASA's Solar Dynamics Observatory (SDO) was launched.

The SDO observes the Sun in order to understand the ways in which it affects the Earth, such as space weather
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On this day in 2001 – February 12th – NASA's NEAR Shoemaker spacecraft landed on the asteroid 433 Eros.

NEAR - Shoemaker was the first spacecraft ever to make a soft landing on an asteroid.
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On this day in 1852 – February 13th – Johan Dreyer was born in Copenhagen.

Dreyer was a prominent astronomer and writer. He was born in Denmark but became a British citizen. Dreyer is best remembered for his New General Catalogue of Nebulae and Clusters of Stars (based on the Herschel catalogues of nebulae). The catalogue numbers are still in use, prefixed by NGC.
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On this day in 1898 – February 14th – Swiss astronomer and physicist Fritz Zwicky was born in Varna, Bulgaria.

Zwicky studied physics and mathematics at the Swiss Federal Polytechnic in Zurich. In 1925 he immigrated to the United States to work with Robert Andrews Millikan at Caltech, but remained a Swiss citizen all his life. Zwicky was quite eccentric in many ways, but made important contributions in several areas of astronomy, carrying out research at both Mt Wilson and Palomar observatories.
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On this day in 1980 – February 14th – NASA's Solar Maximum mission was launched.

Solar Max was designed to investigate solar phenomena, particularly solar flares.
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On this day in 1990 – February 14th – NASA's Voyager 1 took a Family Portrait, looking towards the Sun from 6 billion km away.

Earth is only one pixel of the image, christened by Carl Sagan "the pale blue dot".
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On this day in 2011 – February 14th – the Stardust-NExT spacecraft made a close flyby of comet Tempel 1.

It was NASA's second visit to Tempel 1, because the Deep Impact mission had visited it in 2005, sending an impactor in order to learn about the comet's interior..
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On this day in 1564 – February 15th – Galileo Galilei was born in Pisa, Italy.

Galileo was one of the first to use a telescope to observe the heavens. He's known for his astronomical discoveries, his experimental physics and, of course, his getting in trouble with the Church.
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On this day in 1973 – February 15th – Pioneer 10 became the first ever spacecraft to cross the asteroid belt.

Pioneer 10 was launched in 1972, and is is now nearly four times farther away from the Sun than Pluto is.
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On this day in 2013 – February 15th – a meteor explosion occurred over Chelyabinsk in Russia causing around 1500 injuries.

The meteoroid was about 20 meters across with a mass of 12,000-13,000 metric tonnes. Fortunately, the explosion occurred high in the atmosphere and the atmosphere absorbed much of the energy. However the shock waves caused a lot of damage, and many of the injuries were from flying glass.
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On this day in 1514 – February 16th – Georg Joachim de Porris was born in Feldkirch in present-day Austria.

The mathematician, astronomer and cartographer, better known as Rheticus, is best remembered for facilitating the publication of De Revolutionibus Orbium Coelestium (On the Revolutions of the Heavenly Spheres) by Copernicus.
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On this day in 1914 – February 16th – Gerard Kuiper discovered Miranda, a moon of Uranus.

It was the first discovery of a Uranian moon since William Lassell's discovery of Ariel and Umbriel in 1851.
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On this day in 1723 – February 17th – German cartographer and astronomer Tobias Mayer was born in Marbach, Württemberg.

Mayer's chart of the full moon was the standard for half a century, but he's best known for his lunar tables. The accuracy of the lunar positions (and the theory behind them) enhanced the lunar distance method for determining longitude at sea. It enabled navigators to find longitude accurately to half a degree.
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On this day in 1996 – February 17th – NASA's NEAR Shoemaker spacecraft was launched.

The spacecraft did a fly-by of asteroid Mathilde and then went on to study asteroid Eros from orbit.
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On this day in 2018 – February 17th – it was the 5,000th sol that NASA's Mars rover Opportunity had been on the red planet.

Opportunity's mission was originally planned for 90 sols. A sol is a Martian day, and it's just over 39.5 minutes longer than an Earth day. A severe planet-wide dust storm in the summer of 2018 would finally end Opportunity's amazing mission.
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On this day in 1677 – February 18th – Jacques Cassini was born at the Paris Observatory.

He was the son of the director of the observatory Jean Dominique Cassini, with whom he made numerous astronomical observations. Eventually, he took over his father's duties as head of the Paris Observatory and continued the astronomical work.
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On this day in 1930 – February 18th – Clyde Tombaugh discovered Pluto.

Pluto was considered to be the ninth planet for many years. It's now the largest known Kuiper Belt object, and is classified as a dwarf planet.
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On this day in 2021 – February 18th – NASA's Perserverance rover arrived safely on Mars at the place now named the Octavia E. Butler Landing.

Perserverance also carried the Mars helicopter Ingenuity.
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On this day in 1473 – February 19th – Nicolaus Copernicus was born in Torun, Poland.

His work De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres) set out his arguments for a heliocentric (sun-centered) system instead of a geocentric (Earth-centered) system.
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On this day in 1986 – February 19th – Mir was launched by the Soviet Union.

Mir was the first modular space station, and was assembled in orbit. It was the first continuously inhabited long-term research station in orbit. The failing station was deorbited in March 2001.
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On this day in 1965 – February 20th – John Glenn became the first American to orbit the Earth.

Glenn's space capsule Friendship 7 took him around the Earth three times before its splashdown.
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On this day in 1744 – February 21st – Frisian astronomer Eise Eisinga was born in Dronrijp, Netherlands.

He built the Koninklijk Eise Eisinga Planetarium at his house in Franeker, Netherlands. The orrery still exists and is the oldest functioning planetarium in the world.
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On this day in 1978 – February 22nd – the first Navstar GPS satellite was launched.

Navstar GPS was what is now called the Global Positioning System (GPS).
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On this day in 1945 – February 23rd – Ukrainian astronomer Svetlana Gerasimenko was born in Baryshivka, Ukraine.

Gerasimenko's name is well known because she was the co-discoverer of comet 67P/Churyumov-Gerasimenko. This was the comet explored by the Rosetta mission . Both the Rosetta spacecraft and its lander Philae are on the comet as it continues to orbit the Sun.
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On this day in 1987 – February 23rd – the light from supernova SN 1987A reached Earth.

The supernova occurred in the Tarantula Nebula in our neighboring galaxy the Large Magellanic Cloud. It was the closest supernova seen in nearly four hundred years, visible to the unaided eye in the southern hemisphere. It has greatly increased our understanding of this spectacular phenomenon.
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On this day in 1990 – February 23rd – Pioneer 11 crossed the orbit of Neptune on its way out of the Solar System.

On that date, the spacecraft went beyond the most distant planet. However, since there are dwarf planets and many other objects beyond Neptune, the spacecraft still hadn't left the Solar System. It's now nearly 112 times farther from the Sun than the Earth is.
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On this day in 1968 – February 24th – the discovery of the first pulsar was announced. However, it wasn't until later that astronomers understood what the object was and gave it its name.

We now know that the mystery objects are fast-rotating neutron stars that emits a beam of electromagnetic radiation. We can only detect one when it's pointing towards us, rather like a lighthouse, so it seems to pulse. A neutron star is the remnant of a massive star following the collapse of its core in a supernova explosion.
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On this day in 1670 – February 25th – German astronomer Maria Margarethe Kirch (née Winckelmann) was born in Panitzsch near Leipzig.

Maria made extensive observations and published accounts of them. She was the first woman now known to have discovered a comet. However, her husband – a well known astronomer – was given the credit.
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On this day in 1786 – February 26th – François Arago was born at Estagel near Perpignan in France.

This extraordinary man was a prominent astronomer, mathematician and physicist, as well as an enlightened politician. He aided in the project of surveying the Paris meridian, and later served as director of the Paris Observatory for over twenty years.
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On this day in 1842 – February 26th – Camille Flammarion, French astronomer and author, was born in Val-de-Meuse.

Flammarion produced over fifty books, including popular books on astronomy, and also some early science fiction novels.
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On this day in 1897 – February 27th – French astronomer Bernard Lyot was born in Paris.

Bernard Lyot's work brought him major international awards. His most important contributions to astronomy were in solar observing, especially the invention of the coronagraph which makes it possible to observe the Sun's corona without waiting for a total eclipse.
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On this day in 2007 – February 28th – the New Horizons spacecraft flew past Jupiter en route to Pluto.

New Horizons made over 700 observations of the Jovian system, but the main reason for the flyby was to carry out a gravity assist maneuver. That boosted the speed of the spacecraft to get it to Pluto five years earlier than it would have otherwise.
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On this day in 1927 – March 1st – American astronomer George Abell was born in Los Angeles, California.

Abell's catalogue of galaxy clusters from the Palomar Sky Survey remains an important piece of work. But in addition to being an active professional astronomer, he was a teacher, administrator, writer and science popularizer.
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On this day in 1965 – March 1st – the first foundation piles were laid for ESTEC (European Space Research and Technology Centre) at Noordwijk in the Netherlands.

ESTEC is the European Space Agency's main technology development and test centre for spacecraft and space technology.
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On this day in 1966 – March 1st – the Soviet probe Venera 3 landed on Venus, the first Earthly craft to land on another planet.

Unfortunately, when the probe entered the atmosphere, ground control lost contact with the orbiting spacecraft. Therefore any data it may have collected couldn't be transmitted.
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On this day in 1982 – March 1st – the descent stage of Soviet probe Venera 13 landed on Venus.

It was the first Venusian probe to transmit color pictures from the surface of the planet. Designed to survive for half an hour, it transmitted for 127 minutes.
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On this day in 1972 – March 2nd - NASA's Pioneer 10 was launched.

Pioneer 10 was the first spacecraft to cross the Asteroid Belt and it carried out the first mission to Jupiter. It's now about 133 AU from Earth, heading out of the Solar System in the direction of the constellation Taurus.
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On this day in 2004 – March 2nd – the European Space Agency (ESA) launched the Rosetta spacecraft.

Rosetta would travel for ten years and billions of miles in order to rendezvous with comet 67P/Churyumov-Gerasimenko, accompany it as it moved through the inner Solar System past the Sun, and also deploy a lander. The mission ended with the spacecraft landing on the comet.
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On this day in 1923 – March 4th – Sir Patrick Moore, English amateur astronomer, writer and broadcaster, was born in Pinner, Middlesex.

He was a prolific author, but was probably best known as the enthusiastic and knowledgeable presenter of the BBC TV program The Sky at Night, which he began in 1957. Although Sir Patrick died in 2012, the program goes on and is the world's longest-running television series.
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On this day in 1979 – March 4th – Jupiter's rings were discovered in images from the Voyager 1 spacecraft.

The rings are dark and made up mainly of dust, so had not been seen from Earth.
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On this day in 1512 – March 5th – Gerardus Mercator was born in Rupelmonde, Kruibeke in what is now Belgium.

Mercator was a German-Flemish cartographer, geographer and cosmographer. He created the 1569 world map based on a new projection that represented sailing courses of constant bearing as straight lines - an innovation that is still employed in nautical charts.
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On this day in 2005 – March 5th – the European Space Agency (ESA) officially inaugurated its first deep space ground station.

The New Norcia facility in Western Australia was the first, but it's since been joined by stations in Spain and Argentina. Deep space tracking stations are essential for missions such as Rosetta and Mars Express.
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On this day in 1787 – March 6th – Joseph Fraunhofer was born in Straubing, Germany.

Fraunhofer was an optician who was known for the quality of his optical glass and excellent telescope objectives. His name is still known today for his discovery of the dark absorption lines - known as Fraunhofer lines - in the Sun's spectrum.
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On this day in 1937 – March 6th – Valentina Tereshkova was born in Bol'shoe Maslennikovo, Russia.

Tereshkova, the first woman in space, was a Soviet cosmonaut who spent three days orbiting in Vostok 6.
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On this day in 1792 – March 7th – polymath John Herschel was born in Slough, Berkshire, England.

Son of the discoverer of Uranus, John Herschel was one of the 19th century's most distinguished individuals. He was a brilliant mathematician, chemist and astronomer, as well as an accomplished artist, author, musician and linguist.
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On this day in 1831 – March 7th – King William IV signed a Royal Charter for the Astronomical Society of London, and it assumed the name Royal Astronomical Society.

William IV also agreed to be the Society's patron; every subsequent British monarch has followed suit.
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On this day in 1837 – March 7th – Henry Draper was born in Prince Edward County, Virginia, USA.

Draper was a doctor, amateur astronomer and pioneer of astrophotography. Following his early death, his wife Anna donated money to Harvard College Observatory to complete his catalogue of stellar spectra. If you see a deep sky object named with an "HD" prefix, it refers to this catalogue.
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On this day in 1804 – March 8th – American astronomer and telescope maker Alvan Clark was born in Ashfield, Massachusetts.

In 1846 he founded Alvan Clark & Sons, which made astronomical telescopes and instruments. Notably, the company made the lenses for large refracting telescopes at Lick Observatory and Yerkes Observatory.
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On this day in 1564 – March 9th – German pastor and amateur astronomer David Fabricius was born in Esens.

Along with his son Johannes, David Fabricius discovered Mira, the first known periodic variable star. They also made the first confirmed observations of sunspots.
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On this day in 1934 – March 9th – Soviet pilot and cosmonaut Yuri Alekseyevich Gagarin was the first human in space.

Yuri Gagarin was born in Klushino, a village in Smolensk Oblast, Russia.
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On this day in 1979 – March 9th – NASA astronomer Linda Morabito discovered evidence of volcanic activity on Jupiter's moon Io.

She found the picture of the first active volcano known outside Earth among the images sent back by Voyager 1
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On this day in 1977 – March 10th – rings were discovered around the planet Uranus.

The rings were found by a team of astronomers who were using the occultation by Uranus of star SAO 158687 to study the planet's atmosphere.
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On this day in 1811 – March 11th – French mathematician and astronomer Urbain LeVerrier was born in Saint-Lô.

LeVerrier's calculations enabled the Berlin Observatory to discover the planet Neptune.
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On this day in 1835 – March 12th – Canadian-American mathematician and astronomer Simon Newcomb was born in Wallace, Nova Scotia.

Newcomb made important contributions to international timekeeping and other fields in applied mathematics such as economics and statistics. He was a professor at the United States Naval Observatory and at Johns Hopkins.
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On this day in 1781 – March 13th – William Herschel discovered the planet Uranus.

He was the first person in history to discover a new planet.
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On this day in 1885 – March 13th – Percival Lowell was born in Boston, Massachusetts.

Lowell was an American businessman, author, mathematician, and astronomer. He founded the Lowell Observatory in Flagstaff, Arizona and began the effort that led to the discovery of Pluto 14 years after his death.
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On this day in 1835 – March 14th – Italian astronomer Giovanni Schiaparelli was born in Savigliano.

Schiaparelli produced the most detailed map of Mars ever published, and it became a standard reference in planetary cartography. When he referred to canali (channels) on Mars, it was translated into English as canals, and Percival Lowell and others were convinced that there was an advanced civilization on Mars.
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On this day in 1879 – March 14th – Albert Einstein was born in Ulm, Württemberg, Germany.

Einstein is definitely a man who needs no introduction.
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On this day in 1935 – March 14th – Apollo astronaut Eugene Cernan was born in Chicago, Illinois.

Cernan, the commander of Apollo 17, was the last man on the Moon.
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On this day in 2016 – March 14th – Part 1 of the joint ESA/Roscosmos ExoMars astrobiology mission was launched.

The launch of the spacecraft containing ExoMars Trace Gas Orbiter (TGO) and Schiaparelli lander was successful. (TGO is now in orbit around Mars, but the lander crashed.) The mission has seen been suspended due to political tensions regarding the Russian invasion of the Ukraine.
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On this day in 1713 – March 15th – French astronomer Nicolas-Louis de Lacaille was born in Rumigny.

Lacaille was one of astronomy's greats. He surveyed nearly 10,000 stars in the southern hemisphere, and invented fourteen new constellations still in use today.
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On this day in 1932 – March 15th – Apollo astronaut Alan Bean was born in Wheeler, Texas.

Bean was the Apollo 12 lunar module pilot, and the fourth person to walk on the Moon.
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On this day in 1750 – March 16th – Caroline Herschel was born in Hanover, Germany.

Bean was the Apollo 12 Caroline Herschel was an assistant to her brother William. She also discovered eight comets and a number of deep-sky objects. She was the first woman to be awarded a Gold Medal by the Royal Astronomical Society.
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On this day in 1899 – March 17th – American astronomer William Henry Pickering discovered Phoebe, the ninth satellite of Saturn.

It was the first moon ever to be discovered photographically. Pickering spotted it on a photographic plate taken in August 1989 at Harvard College Observatory's station near Arequipa, Peru.
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On this day in 1930 – March 17th – Apollo astronaut Jim Irwin was born was born in Pittsburgh, Pennsylvania.

Irwin was the Apollo 15 lunar module pilot and eighth person to walk on the Moon.
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On this day in 2011 – March 17th – NASA's Messenger spacecraft went into orbit around Mercury.

Messenger was the first spacecraft ever to orbit Mercury.
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On this day in 1965 – March 18th – the Soviet spacecraft Voskhod 2 was launched.

On this mission, cosmonaut Alexei Leonov became the first person to leave a spacecraft for a "spacewalk".
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On this day in 1799 – March 19th – the English physician, clergyman and astronomer William Rutter Dawes was born in London.

Dawes is probably best known for the Dawes' Limit, the formula he devised to determine the theoretical limit of the resolving power of a telescope. For his research into double stars the Royal Astronomical Society presented him with their Gold Medal in 1855.
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On this day in 1958 – March 20th – the London Planetarium opened to the public.

For nearly half a century the planetarium received school children and tourists with presentations about astronomy and space. The planetarium was part of the site of Madame Tussauds, and the owners closed it in 2006 in order to use the area for entertainment presentations.
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On this day in 1865 – March 21st – Antonia Maury was born in Cold Stream, New York.

She is best remembered for her work at Harvard College Observatory. Her stellar classification system allowed Danish astronomer Ejnar Hertzsprung to show the evolution of stars.
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On this day in 1997 – March 22nd – Comet Hale-Bopp made its closest approach to Earth.

The two-tailed comet was probably the most widely observed comet of the twentieth century. It's also known as the Great Comet of 1997.
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On this day in 1749 – March 23rd – Pierre-Simon Laplace was born in Beaumont-en-Auge, France.

Laplace was a brilliant French mathematician, astronomer, and physicist who is sometimes called "France's Newton". He accounted for the observed deviations of planets from their theoretical orbits by applying Newton's theory of gravitation to the problem.
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On this day in 1840 – March 23rd – American polymath John William Draper produced the first detailed photograph of the Moon.

It was the first astronomy photograph taken in North America.
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On this day in 2001 – March 23rd – the Soviet/Russian space station Mir was deorbited.

Mir was the first space station assembled in orbit and the first continuously inhabited long-term orbital research station.
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On this day in 1893 – March 24th – German astronomer Walter Baade was born in Preußisch Oldendorf, Germany.

Baade, who worked at Mt Wilson Observatory in California for many years, defined two distinct populations of stars, and his discovery that there are two types of Cepheid variable star meant that his recalculation of the known universe doubled the size calculated by Hubble.
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On this day in 1665 – March 25th – Christiaan Huygens discovered Saturn's moon Titan.

The European Space Agency (ESA) Titan lander was named after Huygens, who was a prominent 17th century Dutch mathematician and scientist.
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On this day in 1883 – March 25th – American astronomer Earl Carl Slipher was born in Mulberry, Indiana.

As did his older brother Vesto, Earl Slipher worked at Lowell Observatory throughout his career. He was a noted planetary astronomer and a pioneer in planetary photography. The lunar crater Slipher on the Moon's far side honors both brothers.
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On this day in 1928 – March 25th – Apollo astronaut Jim Lovell was born in Cleveland, Ohio.

Lovell flew on Gemini 7 and Gemini 12. As a member of the crew of Apollo 8, he was one of the first three humans to orbit the Apollo 8, and Apollo 13. As the commander of Apollo 13, he was part of one of the most dramatic missions in NASA history.
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On this day in 1773 – March 26th – self-educated American mathematician and astronomer, Nathaniel Bowditch, was born in Salem, Massachusetts.

His greatest contribution to science was his translation of Laplace’s five-volume Mécanique Céleste [Celestial Mechanics]. It earned him an international reputation and was of great importance in the development of astronomy in the United States.
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On this day in 1972 – March 27th – the Soviet probe Venera 8 was launched.

Venera 8 made the first completely successful landing on Venus, and sent data from the surface for fifty minutes before succumbing to the intense pressure and searing temperature.
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On this day in 1802 – March 28th – Heinrich Olbers, German physician and astronomer, discovered Pallas.

Pallas was the second asteroid to be discovered, and it was counted as a planet at the time, as Ceres had been.
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On this day in 1807 – March 29th – Heinrich Olbers, German physician and astronomer, discovered Vesta.

Olbers discovered Vesta almost exactly five years to the day after his discovery of Pallas. Vesta was the third asteroid to be discovered, and it was also counted as a planet at the time. Like Ceres, it's been visited by NASA's Dawn mission.
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On this day in 1879 – March 30th – the German lens maker Bernhard Woldemar Schmidt was born near Tallinn in Estonia.

His name lives on in the Schmidt telescopes. He invented a telescope mirror that let astronomers get sharp wide-field images of the sky with a single exposure. They are still widely used. The best known one is probably the 48-inch Samuel Oschin Telescope at Palomar Observatory, completed in 1948.
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On this day in 1596 – March 31st – René Descartes was born at La Haye, Touraine, France.

The French philosopher-mathematician was a key figure in the development of 17th century cosmology.
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On this day in 2005 – March 31st – the dwarf planet Makemake was discovered by Michael E. Brown, Chadwick A. Trujillo and David L. Rabinowitz.

Makemake derives its name from a creator deity in the mythology of the Rapa Nui people of Easter Island.
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On this day in 1990 – April 1st – the NASA/ESA Hubble Space Telescope was installed in the cargo bay of the Space Shuttle Discovery for the STS-31 mission, ready for launch.

Discovery launched on April 24th from NASA's Kennedy Space Center.
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On this day in 1997 – April 1st – Comet Hale-Bopp made its closest approach to the Sun.

The comet was dubbed the Great Comet of 1997 and was probably the most widely observed comet of the 20th century.
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On this day in 1845 – April 2nd – French physicists Leon Foucault and Louis Fizeau took the first successful photograph of the Sun.
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On this day in 1867 – April 3rd – German astronomer Wilhelm Tempel, observing in Marseilles, discovered Comet 9P/Tempel 1.

Discovery in 2005 the comet was the target of NASA's Deep Impact probe.
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On this day in 1966 – April 3rd – the Soviet spacecraft Luna 10 was inserted into orbit around the Moon.

It was the first spacecraft to go into orbit around the Moon, and the first human-made object to orbit a body beyond the Earth.
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On this day in 2014 – April 3rd – ESA satellite Sentinel 1-A was launched from Europe's spaceport in French Guiana, the first in the Copernicus EU programme.

Copernicus is the world's largest Earth observation programme, monitoring many aspects of the environment.
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On this day in 1809 – April 4th – American astronomer and mathematician Benjamin Peirce was born in Salem, Massachusetts.

He graduated from Harvard University where he also obtained his M.A. Peirce was appointed Harvard’s first Perkins Professor of Mathematics and Astronomy. He played a key role in the development of the Harvard College Observatory and carried out a great deal of important observational work, including helping to determine the orbital path of the newly discovered planet Neptune.
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On this day in 1914 – April 4th – Czech astronomer Zdeněk Kopal was born in Litomyšl, Czechoslovakia (now the Czech Republic).

In 1938 he studied in England at Cambridge under Arthur Eddington, and later that year accepted a teaching post at Harvard College Observatory. In order to ensure good quality maps of the Moon for the Apollo program, Kopal organised a USAF-funded programme designed to map the Moon from the Earth using high resolution imagery. He was head of astronomy at the University of Manchester for 30 years and Editor-in-Chief of the journal Astrophysics and Space Science from its foundation in 1968 until his death in 1993.
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On this day in 1622 – April 5th – Italian mathematician and scientist Vincenzo Viviani was born in Florence.

From 1639 until 1642 he was a student, secretary and assistant of Galileo, who was under house arrest. In 1657, Viviani became a co-founder of the Accademia del Cimento (Academy of Experiment), an early scientific society which came into being three years before the Royal Society was founded in England
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On this day in 1965 – April 6th – Intelsat I became the first commercial communications satellite to be placed in geosynchronous orbit.

It was nicknamed Early Bird from the proverb "The early bird catches the worm." Although the satellite remains in orbit, the last time it was activated was in 1990.
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On this day in 1991 – April 7th – the Compton Gamma Ray Observatory (CGRO) was deployed by astronauts on the Space Shuttle Atlantis.

It was the second of NASA's "Great Observatories" and it transformed our knowledge of the high-energy sky, producing the first ever all-sky survey in gamma rays.
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On this day in 2001 – April 7th – NASA's Mars Odyssey orbiter was launched.

The orbiter was designed to look for evidence of past or present water and ice, as well as study the planet's geology and radiation environment. Its primary mission was meant to last 32 months, but it's still in service, and holds the record for the longest continually active spacecraft in orbit around a planet other than Earth.
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On this day in 1793 – April 8th – German amateur astronomer Karl Ludwig Hencke was born in Driesen, Brandenburg.

Hencke discovered five variable stars and carried out much useful work on the general improvement of star charts. But his major discoveries were the asteroids Astraea (1845), found 15 years after his search began, and Hebe in 1847. They were the first new asteroids known since the discovery of Vesta was in 1807.
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On this day in 1964 – April 8th – NASA's Gemini 1 was launched as an unmanned test flight.

The Gemini program was the bridge between NASA's Mercury program - its original ventures in manned spaceflight - and the Apollo moon program.
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On this day in 1921 – April 9th – Mary Jackson was born in Hampton, Virginia.

Jackson was NASA's first black female engineer. She began as a computer for NASA's predecessor organization, but went on to take advanced engineering classes. She worked at Langley Research Center in Hampton, Virginia, for most of her career.
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On this day in 1959 – April 9th – NASA selected its first group of astronauts, known as the Mercury Seven.

They were the pioneers of the US manned space program: Scott Carpenter, Gordon Cooper, John Glenn, Gus Grissom, Wally Schirra, Alan Shepard, and Deke Slayton. None of the Mercury Seven are still with us.
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On this day in 1968 – April 9th – Europe's spaceport, the Centre Spatial Guyanais (CSG) - Guiana Space Centre - became operational.

This first launch was of a sounding rocket from the French Veronique series.
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On this day in 1919 – April 10th – American aerospace engineer John C. Houbolt was born in Altoona, Iowa.

Houbolt led the team behind the lunar orbit rendezvous (LOR) that was used to land humans on the Moon and return them to Earth. Using LOR, NASA saved time and billions of dollars by efficiently using existing rocket technology.
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On this day in 1960 – April 11th – Project Ozma began.

Cornell University astronomer Frank Drake initiated this project. It was a pioneering SETI (Search for ExtraTerrestrial Intelligence) experiment that searched for signs of life in distant planetary systems by monitoring interstellar radio waves.
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On this day in 1970 – April 11th – NASA's Apollo 13 Moon mission was launched.

This was the ill-fated mission that didn't make it onto the Moon, but with the assistance of a lot of smart and dedicated people, the astronauts made it safely back to Earth. The crew does however hold the record for having travelled the farthest distance into space of any humans. They were 400,171 km (248,655 mi) away from Earth on April 14, 1970.
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On this day in 1984 – April 11th – the crew of the space shuttle Challenger redeployed the astronomy Solar Max satellite.

The astronauts had retrieved the malfunctioning satellite and repaired it, the first time a satellite was repaired in space.
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On this day in 1986 – April 11th – Halley's Comet was at its closest to the Earth

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On this day in 2006 – April 11th – ESA's Venus Express was inserted into orbit around Venus.

The mission provided an enormous amount of data on the Venusian atmosphere until the European Space Agency concluded it in December 2014. In addition to helping to understand the atmosphere of Venus, it also contributed to an a general understanding of atmospheric dynamics in general, including climate change on Earth.
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On this day in 1961 – April 12th – Soviet cosmonaut Yuri Gagarin became the first spaceman.

Gagarin made the historic first orbit of the Earth in the Vostok 1 craft.
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On this day in 1851 – April 12th – English astronomer Edward Walter Maunder was born in London.

He was a founder member of the British Astronomical Association, but is probably best remembered for his solar observing and the study of sunspots, in particular his discovery that very few sunspots had been seen during the years 1645 to 1715. This period is now known as the Maunder Minimum.
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On this day in 1579 – April 13th – Giovanni Battista Hodierna was born in Ragusa, Sicily.

Hodierna was an astronomer at the court of the Duke of Montechiaro in Piedmont, Italy. Pre-dating Charles Messier by over a century, he compiled a sky catalog that included a number of nebulous objects that might be confused with comets.
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On this day in 1629 – April 14th – Dutch scientist, mathematician and inventor, Christiaan Huygens, was born in The Hague.

Huygens was a prominent scientist in his day. His varied contributions included the invention of the pendulum clock, and the discovery of Saturn's moon Titan. ESA (European Space Agency) named its Titan lander after him.
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On this day in 1868 – April 14th – Irish astronomer and mathematician Annie Scott Dill Maunder (née Russell) was born in Strabane, County Tyrone.

She worked at Greenwich Observatory, but had to give up her job when she married her colleague Edward Maunder. However they made a formidable team, going on solar eclipse expeditions together and collaborating on publications. Annie also served as editor of the Journal of the British Astronomical Society and was one of the first women to become a fellow of the Royal Astronomical Society.
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On this day in 1972 – April 16th – Apollo 16 was launched.

It was crewed by Commander John Young, Lunar Module Pilot Charles Duke, and Command Module Pilot Ken Mattingly.
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On this day in 1598 – April 17th – Italian astronomer Giovanni Battista Riccioli was born in Ferrara.

Riccioli is best known for the Almagestum Novum published in 1651. It included his Moon map and over 1500 folio pages densely packed with text, tables and illustrations. The work became a standard technical reference book for astronomers all over Europe and included the names of prominent lunar features still in use today.
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On this day in 2014 – April 18th – NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) was intentionally crashed into the Moon at end of its mission.

LADEE, orbiting the Moon's equator, studied the lunar exosphere and dust in the Moon's vicinity. It was crashed on the far side of the Moon to ensure that it didn't damage historically important landing sites on the near side.
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On this day in 1971 – April 19th – Salyut 1 was launched by the Soviet Union.

It was the first ever manned space station.
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On this day in 2021 – April 19th – NASA's Mars helicopter Ingenuity lifted into the Martian sky for the first time.

It was the first time ever an aircraft flew on a world beyond Earth.
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On this day in 1967 – April 20th – NASA's Surveyor 3 unmanned probe landed on the Moon.

In November 1969, Apollo 12 astronauts Charles Conrad and Alan Bean landed near the probe and removed some parts to return them to Earth.
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On this day in 1724 – April 22nd – the German philosopher Immanuel Kant was born in Königsberg [now Kaliningrad, Russia].

His theoretical work in astronomy and cosmology anticipated and inspired later discoveries about our Galaxy and others, including the idea that the Solar System was a part of a system of stars constituting a lens-shaped galaxy, and that there were many other galaxies scattered throughout and making up the whole Universe.
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On this day in 1858 – April 23rd – Max Planck was born in Kiel, Germany.

Planck was a theoretical physicist best known as the originator of quantum theory. His work won him the Nobel Prize in Physics in 1918. The European Space Agency (ESA) named a space observatory for him - it mapped the cosmic microwave background from 2009-2013.
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On this day in 1957 – April 24th – in Britain, the first ever broadcast of the BBC's monthly documentary television program, The Sky at Night, was aired.

The show was presented by Patrick Moore from its first airing until his death in 2012. It's been the longest-running program with the same presenter in television history, and continues to air with various astronomers presenting.
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On this day in 1970 – April 24th – China became the fifth nation to launch its own satellite.

The satellite Dongfanghong I had a design life of 20 days. During that time, it transmitted telemetry data and space readings to the Earth.
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On this day in 1990 – April 25th – the Hubble Space Telescope was deployed.

The Space Shuttle Discovery successfully launched the telescope during its STS-31 mission.
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On this day in 1920 – April 26th – the Shapley-Curtis debate took place regarding the nature and distance of "spiral nebulae".

Even in 1920, we didn't know what the "spiral nebulae" were. Were they objects in our Milky Way galaxy and therefore comparatively close? Or were they "island universes", i.e., other galaxies, and therefore at a great distance?
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On this day in 2017 – April 26th – the Cassini spacecraft made the first dive of the Grande Finale of its 13-year study of the Saturnian system.

It was the first of a series of close orbits that involved Cassini diving between Saturn and its rings. Astronomers collected data to learn more about the origins, mass, and age of Saturn's rings, as well as the mysteries of the gas giant's interior.
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On this day in 1900 – April 28th – Dutch astronomer Jan Oort was born in Franeker, Netherlands.

Oort made major contributions to the understanding of the Milky Way and was a pioneer in radio astronomy. He realized that the orbits of comets "implied there was a lot more solar system than the region occupied by the planets." The Oort cloud of comets that surrounds the Solar System was named for him.
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On this day in 1906 – April 28th – Dutch-American astronomer Bart Bok was born in Hoorn, Netherlands.

He's best known for his work on the structure and evolution of our Galaxy and the dark nebulae named for him. Click here to learn more about Bok globules.
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On this day in 1928 – April 28th – American geologist and planetary scientist Gene Shoemaker was born in Los Angeles, California.

Shoemaker was one of the founders of the study of planetary science. And along with his wife Carolyn and David Levy, he was co-discoverer of Comet Shoemaker-Levy 9 which hit Jupiter.
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On this day in 2003 – April 28th – NASA's Galaxy Evolution Explorer (GALEX) was launched.

GALEX, which operated until early 2012, was an orbiting space telescope observing galaxies in ultraviolet light. Its observations provided data about how galaxies - the basic structures of our Universe - evolve and change.
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On this day in 1682 – May 1st – the Paris Observatory was inaugurated by Louis XIV.

It's one of the oldest - and the oldest still active - astronomical centres in the world.
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On this day in 1949 – May 1st – Gerard Kuiper discovered Neptune's moon Nereid.

Nereid was the second known moon of Neptune. It was discovered over a century after William Lassell discovered the first moon, Triton.
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On this day in 1996 – May 1st – Comet Hyakutake made its closest approach to Sun.

It's known as The Great Comet of 1996. its passage near the Earth was one of the closest cometary approaches of the previous 200 years.
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On this day in 1989 – May 4th – NASA's Magellan spacecraft was released by Space Shuttle mission STS-30 Atlantis, the first interplanetary mission to be so launched.

The spacecraft, often referred to as the Venus Radar Mapper, went on to map the surface of Venus using synthetic aperture radar which is able to penetrate the planet's thick clouds.
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On this day in 2002 – May 4th – NASA launched the Aqua scientific research satellite.

Aqua was the second major component of the Earth Observing System (EOS), and was designed to study the precipitation, evaporation and cycling of water.
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On this day in 1961 – May 5th – Alan Shepard became the first American in space, making a suborbital flight in Freedom 7.

Ten years later Shepard walked on the Moon as the commander of Apollo 14.
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On this day in 1872 – May 6th – Dutch astronomer and mathematician Willem de Sitter was born in Sneek, Netherlands.

He is best remembered for his contributions to cosmology, in particular for showing that a universe containing very little matter would expand. This paved the way for later research carried out by the American astronomer Edwin Hubble who was to provide observational evidence that the universe is expanding. De Sitter's work was honored with two prestigious awards, the Gold Medal of the Royal Astronomical Society and the Bruce Medal of the Astronomical Society of the Pacific.
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On this day in 1900 – May 9th – Cecilia Payne-Gaposchkin was born in Wendover, Buckinghamshire, England.

Cecilia Payne was the first woman to earn a PhD in astronomy from Radcliffe College of Harvard University. And in her PhD thesis, she was the first person to propose that stars were composed mainly of hydrogen and helium.
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On this day in 2003 – May 9th – the Japanese spacecraft Hayabusa ("peregrine falcon") was launched.

Hayabusa was the first mission to return a sample of material from an asteroid.
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On this day in 1915 – May 11th – Einstein's General Theory of Relativity was published.

Einstein's theory has often been tested and has passed every test - it's changed the way we view the cosmos.
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On this day in 2009 – May 11th – space shuttle mission STS-125 was launched.

STS-125 was the fifth and final servicing mission for the Hubble Space Telescope.
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On this day in 1930 – May 12th – the Adler Planetarium opened in Chicago.

It was the first planetarium in the western hemisphere.
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On this day in 1973 – May 14th – NASA launched Skylab.

It was the first US space station, and it included a workshop, a solar observatory, and several hundred life science and physical science experiments.
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On this day in 2009 – May 14th – the European Space Agency (ESA) launched the Planck Space Observatory.

Launched along with the Herschel Space Observatory, from 2009-2013 Planck made high resolution studies of the cosmic microwave background radiation left over from the very early Universe.
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On this day in 2009 – May 14th – the European Space Agency (ESA) launched the Herschel Space Observatory (HSO), along with Planck.

HSO was a space-based telescope to study the Universe by the light of the far-infrared and submillimeter portions of the spectrum. It was named for William Herschel who discovered the infrared. The telescope was decommissioned in 2013 when the coolant ran out. It had been the largest infrared telescope ever launched until the launch of the James Webb Space Telescope in 2021.
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On this day in 1718 – May 15th –Johannes Kepler discovered the simple mathematical rule governing the orbits of the solar system's planets, now recognized as Kepler's Third Law of planetary motion.

Kepler's three laws described the orbital motions of the planets in a solar system where they orbited the Sun, not the Earth.
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On this day in 1857 – May 15th – Scottish-American astronomer Williamina Fleming was born in Dundee, Scotland.

Fleming, a computer at Harvard College Observatory, was a pioneer in the classification of stellar spectra. During the course of her career, she also discovered 10 novae, 52 nebulae, and 310 variable stars.
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On this day in 1925 – May 16th – American astronomer Nancy Grace Roman was born in Nashville, Tennessee.

One of the first female executives at NASA, Roman is known to many as the "Mother of Hubble" for her role in planning the Hubble Space Telescope. NASA's infrared space telescope, currently in development, is named for her.
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On this day in 1836 – May 17th – English scientist and astronomer Norman Lockyer was born in Rugby, England.

Lockyer and French scientist Pierre Janssen independently discovered the gas helium in the light spectrum of the Sun decades before any was found on Earth.
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On this day in 1968 – May 17th – the first ESRO satellite was successfully launched.

The European Space Research Organisation (ESRO) was a precursor to the European Space Agency (ESA). ESRO-2B was launched by a Scout rocket from the Western Test Range in California. It was the first mission controlled by teams at the European Space Operations Centre in Darmstadt, Germany.
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On this day in 1974 – May 17th – NASA launched the first ever geostationary satellite.

SMS-1 (Synchronous Meteorological Satellite) was the first satellite in the first series of geostationary meteorological satellites. (A geostationary satellite is in an orbit that keeps it above the same part of the Earth all of the time.)
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On this day in 1711 – May 18th – astronomer, mathematician, philosopher and Jesuit priest, Roger Joseph Boscovich, was born in Ragusa (Dubrovnik) in what is modern-day Croatia.

Boskovich wrote on a wide range of astronomical topics, including the Aurora Borealis, transits of Mercury, and the theory of the telescope. Among other accomplishments, he solved the problem of locating the Sun's equator, observed sunspots to determine the rotation period of the Sun, and discovered the absence of an atmosphere on the Moon.
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On this day in 1991 – May 18th – British cosmonaut Helen Sharman was launched into space on board a Soyuz spacecraft.

Sharman was the first Briton (and first Western European woman) in space. With crew mates Anatoli Artsebarsky and Sergei Krikalev, she orbited Earth for two days before docking with the Mir space station.
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On this day in 2009 – May 18th – the final spacewalk to service the Hubble Space Telescope took place.

The servicing mission was carried out in mission STS-125 aboard the shuttle Atlantis. There were five spacewalks altogether, the final one carried out by astronauts John Grunsfeld and Andrew Feustel.
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On this day in 1825 – May 20th – American astronomer George Phillips Bond was born in Dorchester, Massachusetts.

He succeeded his father, William Cranch Bond, as director of Harvard College Observatory. And he is considered by many to be the father of astrophotography, his achievements including taking the first photograph of a star (Vega in 1850), and in 1857 of the double star Alcor and Mizar in Ursa Major.
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On this day in 1990 – May 20th – the Hubble Space Telescope sent back its first image, that of several stars, captured with its Wide Field/Planetary Camera.

Unfortunately, it was then discovered that there was a flaw in the main mirror which meant fuzzy images for three years until the first space shuttle servicing mission. Interestingly, the images were still much better than the ones from ground-based telescopes of the time.
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On this day in 2010 – May 21st – the Japanese experimental aircraft IKAROS was launched.

IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) is the first spacecraft to successfully demonstrate solar sail technology in interplanetary space.
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On this day in 1961 – May 25th – President John F. Kennedy challenged the USA to "commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth."

Sadly, Kennedy didn't live to see it happen.
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On this day in 2008 – May 25th – NASA's Phoenix lander landed on Mars.

Phoenix was expected to spend 90 Martian sols searching for environments suitable for microbial life. It carried out its mission for 157 Martian sols. (A sol is a Martian day - it's about 40 minutes longer than an Earth day).
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On this day in 1951 – May 26th – the first American woman in space, Sally Ride, was born in Encino, California.

Ride – physicist, engineer, educator and astronaut – made her first flight almost twenty years to the day after cosmonaut Valentina Tereshkova became the very first woman in space.
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On this day in 1983 – May 26th – ESA's X-ray observatory, Exosat, was launched.

Exosat was the first European Space Agency mission to study the Universe at X-ray wavelengths, and one of the first unmanned satellites to feature an onboard computer. The spacecraft was operational from May 1983 to April 1986.
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On this day in 1931 – May 27th – Swiss physicist and explorer Auguste Piccard, with Paul Kipfer, became the first persons to travel into the stratosphere.

They reached a record altitude in a balloon with a pressurized aluminum gondola designed by Piccard. Piccard wanted to measure the activity of cosmic rays and investigate Einstein's theory of relativity.
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Explorers have to be daring.

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On this day in 1912 – May 28th – Australian radio astronomer Ruby Payne-Scott was born in Grafton, New South Wales.

She worked on radar systems in World War II, and post war helped to lay the foundations for radio astronomy. Payne-Scott was the first woman radio astronomer.
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On this day in 1794 – May 29th – German astronomer Johann Heinrich von Mädler was born in Berlin.

Von Mädler, along with Wilhelm Beer, published Mappa Selenographica. It was the most complete map of the Moon at that time, and it remained unsurpassed for over forty years.
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On this day in 1919 – May 29th – Einstein's General Theory of Relativity was tested during a total solar eclipse.

By comparing the apparent distance between stars in the constellation Taurus, with and without the Sun between them, British astrophysicist Arthur Eddington confirmed the theoretical predictions about gravitational lensing.
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On this day in 1925 – May 29th – Irish astronomer Mary Brück, née Conway, was born in Ballivor, County Meath.

Mary Brück was a a senior lecturer at the University of Edinburgh, her astronomical research including investigations of stars, the interstellar medium and the Magellanic Clouds. However she is probably best remembered as a writer, with a particular interest in the history of science and women in astronomy.
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On this day in 1934 – May 30th – cosmonaut Alexi Leonov was was born in Listvyanka, West Siberian Krai, Russian SFSR.

As a cosmonaut, among his accomplishments was his being the first person to carry out a spacewalk. Leonov was also a writer and an accomplished artist.
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On this day in 1959 – May 30th – American geophysicist and planetary scientist Claudia Joan Alexander was born in Vancouver, Canada.

With degrees in geophysics and space physics, Alexander researched as a planetary scientist and was the project manager for the Galileo mission in its final phase. She was also the science coordinator for the Cassini mission to Saturn, and in 200 the project manager for NASA's contribution to the European Rosetta mission to Comet Churyumov-Gerasimenko.
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On this day in 1963 – May 30th – English chemist, astronaut and science communicator, Helen Sharman, was born in Grenoside, Sheffield.

Chosen to train as a cosmonaut, Sharman was the first Briton in space and the first woman to visit the Mir space station.
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On this day in 1975 – May 30th – nine countries signed the convention to establish the European Space Agency (ESA).

The convention came into force on 30 October 1980 with the deposit of the last instrument of ratification.
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On this day in 1877 – May 31st – French astronomer Gabrielle Renaudot Flammarion was born in Meudon in the département of Hauts-de-Seine.

Gabrielle, the second wife of the prominent astronomer Camille Flammarion, was General Secretary of the Société Astronomique de France. She worked with her husband at his observatory at Juvisy-sur-Orge, France from where she carried out observations of planets, minor planets and variable stars. Gabrielle Flammarion published work on several topics including the Great Red Spot on Jupiter and the surface features of Mars.
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On this day in 1858 – June 2nd – Italian astronomer Giovanni Battista Donati first observed the comet that bears his name.

Comet Donati, formally designated C/1858 L1 and 1858 VI, was one of the most brilliant comets of the 19th century. It inspired artists and poets and was also the first comet to be photographed, though the photograph has been lost.
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On this day in 1930 – June 2nd – Apollo astronaut Charles "Pete" Conrad Jr. was born in Philadelphia, Pennsylvania.

Conrad was the commander of the Apollo 12 mission and the third person to walk on the Moon.
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On this day in 1955 – June 2nd – the Baikonur Cosmodrome in Kazakhstan became operational.

It was from here that the first satellite to orbit the Earth was launched, and Yuri Gagarin, the first man to orbit the Earth, was launched into space. It is still the world's largest space launch facility.
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On this day in 1977 – June 2nd – 14 delegates from nations around the world plus the UN Secretary-General recorded greetings for the Voyager space probes' golden record.

Voyagers 1 and 2 were launched a month apart later in the year. Decades later Voyager 1 became the first probe to cross the heliopause into interstellar space.
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On this day in 2003 – June 2nd – ESA's MarsExpress was launched, the first European space mission to go to the Red Planet.

Two decades later, the orbiter is still at work in the Martian sky.
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On this day in 1948 – June 3rd – the 200-inch Hale telescope was dedicated at Palomar Observatory in California.

The telescope was a marvel of design and precision engineering, and the largest in the world for several decades.
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On this day in 2000 – June 4th – the Compton Gamma Ray Observatory reentered the atmosphere.

The observatory, part of NASA's Great Observatories series, detected high energy photons. It reentered the atmosphere in a controlled deorbit.
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On this day in 1819 – June 5th – British mathematician and astronomer John Couch Adams was born in Laneast, Cornwall.

His most famous achievement was predicting the existence and position of Neptune, using mathematics. But Urbain LeVerrier had independently made the calculations and the planet was discovered using LeVerrier's calculations. (Who discovered Neptune?).
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On this day in 1971 – June 6th – Soyuz 11 was launched with the first crew to occupy the Salyut 1 space station.

Salyut 1 was the very first space station - it was launched into low earth orbit by the Soviet Union in April 1971.
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On this day in 1992 – June 7th – the Extreme Ultraviolet Explorer (EUVE) was launched.

This NASA space telescope was the first one designed especially for the short-wave ultraviolet range. It compiled an all-sky survey of 801 astronomical targets.
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On this day in 1625 – June 8th – Italian-French astronomer Giovanni Domenico (Jean-Dominique) Cassini was born in Perinaldo, Italy.

Cassini was one of the most important astronomers of the 17-18th centuries, and was the first of four Cassinis to direct the Paris Observatory. The NASA/ESA/ASI Cassini-Huygens mission to Saturn bore his name because of his study of Saturn, which included the discovery of four of Saturn's moons.
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On this day in 1812 – June 9th – German astronomer Johann Gottfried Galle was born in Radis, Kingdom of Saxony.

Galle is best known for his being the first person to see the planet Neptune, knowing what he was seeing. This followed his search for the planet using the calculations Urbain Le Verrier had sent him. (Who discovered Neptune?)
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On this day in 1975 – June 9th – the Soviet Union launched the Venera 9 mission.

It consisted of an orbiter and a lander. The orbiter was the first spacecraft to orbit Venus, while the lander was the first to return images from the surface of another planet.
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On this day in 2003 – June 10th – NASA's Mars rover Spirit was launched.

The original plan was for a three-month mission, but the mission wasn't finally terminated until May 2011.
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On this day in 1985 – June 11th – the descent module of the Soviet craft Vega 1 arrived on Venus.

After releasing the descent module, the probe Vega 1 got a gravitational assist from Venus and continued its journey to intercept Comet Halley.
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On this day in 1922 – June 12th – Italian astrophysicist and populariser of science Margherita Hack was born in Florence.

She became a full professor of astronomy at the University of Trieste and the administrator of the Trieste Astronomical Observatory, the first woman in Italy to hold either of such positions. Hack received national and international recognition for her innovations at the observatory and her promotion of astronomy to the public.
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On this day in 1611 – June 13th – the first documented report in Europe on the phenomenon of sunspots was published.

Narration on Spots Observed on the Sun and Their Apparent Rotation with the Sun was the work of Frisian/German astronomer Johannes Fabricius.
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On this day in 1831 – June 13th – Scottish scientist James Clerk Maxwell was born in Edinburgh.

Maxwell showed that electricity, magnetism, and light are all aspects of the same phenomenon, electromagnetism. His discoveries helped usher in the era of modern physics, laying the foundation for such fields as special relativity and quantum mechanics.
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On this day in 1983 – June 13th – Pioneer 10 crossed the orbit of Neptune, our outermost planet.

Pioneer 10 was the first human-made object to leave the proximity of the major planets of the Solar System.
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On this day in 2010 – June 13th – the Japanese spacecraft Hayabusa ("Peregrine Falcon") returned the first ever samples from an asteroid.

Hayabusa had studied asteroid 25143 Itokawa from orbit and then landed on the asteroid to collect small grains of material.
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On this day in 1963 – June 16th – Valentina Tereshkova in Vostok 6 became the first woman in space.

With a single flight, she logged more flight time than the combined times of all American astronauts who had flown before that date. She's the only woman ever to make a solo space flight.
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On this day in 1714 – June 17th – French astronomer and cartographer Caesar-François Cassini de Thury was born in Thury-sous-Clermont in northern France.

He was the grandson of Jean Dominique Cassini - after whom the Cassini mission to Saturn was named - and the third Cassini to be the director of the Paris Observatory.
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On this day in 1800 – June 17th – William Parsons, Third Earl of Rosse, was born in York, England.

As well as being a skilled engineer and ingenious scientist, he was a dedicated astronomer who constructed a 72-inch (1.83 metre) diameter reflecting telescope at Birr Castle, Parsonstown in Ireland during the 1840s. Known as the Leviathan of Parsonstown, this huge telescope was larger than any made previously and the largest in the world for several decades, and enabled him to discover the spiral nature of many nebulae.
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On this day in 1799 – June 18th – English merchant and astronomer William Lassell was born in Bolton, Lancashire.

Lassell was known for his improvements to the reflecting telescope, and his discoveries, which include Neptune's moon Triton and two of the moons of Uranus.
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On this day in 1983 – June 18th – physicist and astronaut Sally Ride became the first American woman in space.

Ride was a crew member of STS-7 Challenger which was launched 2 days after the 20th anniversary of Valentina Tereshkova's space flight.
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On this day in 1667 – June 21st – the meridian line of the Paris Observatory was engraved.

It was decided that the observatory should be built so that the Paris meridian passed through the center of the building, dividing it into two symmetrical parts. Built by order of King Louis XIV, the Paris Observatory was the first national observatory.
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On this day in 1675 – June 24st – the Royal Observatory Greenwich was founded.

The world's Prime Meridian (0 degrees of longitude) now goes through Greenwich.
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On this day in 1915 – June 24st – English mathematician, astronomer and author, Sir Fred Hoyle, was born in Gilstead, Bingley, West Yorkshire.

Hoyle was the first to formulate a theory that explained the creation of chemical elements by nuclear fusion reactions in stars.
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On this day in 1999 – June 24st – NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) was launched.

Operated by the Johns Hopkins University Applied Physics Laboratory, for eight years it detected light in a part of the electromagnetic spectrum which is mostly unobservable by other telescopes.
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On this day in 1894 – June 25th – Hermann Oberth was born in Sibiu, Romania (originally called Hermannstadt, Transylvania).

A German physicist and mathematician, Oberth is considered one of the founding fathers of rocketry and astronautics, along with Tsiolkovsky and Goddard.
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On this day in 1817 – June 26th – French astronomer Charles Messier was born in Badonviller in the Lorraine region of France.

Messier published an astronomical catalogue consisting of 110 nebulae and faint star clusters, which came to be known as the Messier objects. The purpose of the catalogue was to help astronomical observers distinguish between permanent objects and transient visually diffuse objects, like comets, in the sky.
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On this day in 1914 – June 26th – American theoretical physicist and astronomer Lyman Spitzer Jr. was born in Toledo, Ohio.

He was known for his research contributions to understanding star formation and plasma physics, and for his promotion of space telescopes. NASA's Spitzer Space Telescope was named in his honor.
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On this day in 2013 – June 27th – NASA's IRIS (Interface Region Imaging Spectrograph) was launched.

IRIS was designed to investigate the physical conditions of the solar limb, particularly the chromosphere of the Sun.
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On this day in 1912 – June 28th – Australian radio astronomer Ruby Payne-Scott was born in Grafton, New South Wales.

Payne-Scott was a pioneer in radiophysics and radio astronomy, and was the first woman radio astronomer.
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On this day in 1995 – June 28th – the first docking between the Soviet space station Mir and the United States Space Shuttle took place.

Daniel Goldin, chief of NASA, called it the beginning of “a new era of friendship and cooperation” between the U.S. and Russia. It helped to pave the way for the creation of the International Space Station.
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On this day in 1868 – June 29th – George Ellery Hale, American solar astronomer, was born in Chicago, Illinois.

Hale was a key figure in the realization of three major telescopes, the 40-inch refractor at Yerkes Observatory, 60-inch Hale and 100-inch Hooker reflectors at Mount Wilson Observatory, and the 200-inch Hale reflector at Palomar Observatory.
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On this day in 1890 – June 30th – an asteroid impact leveled hundreds of miles of Siberian forest around Tunguska in Russia.

The event is classified as an impact. However, it's now thought to have been caused by an object that exploded above ground, as no impact crater has ever been found. Since 2015, June 30th has been designated International Asteroid Day.
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On this day in 1990 – June 30th – the joint ESA/NASA Ulysses mission came to an end after 18 years in service.

Ulysses was the first ever spacecraft to explore space above and below the Sun's poles. When it was launched it had a nominal lifetime of five years.
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On this day in 2001 – June 30th – NASA's Wilkinson Microwave Anistotropy Probe (WMAP) was launched.

This spacecraft operated from 2001 to 2010. Across the sky it measured tiny temperature differences in the cosmic microwave background (CMB) - the radiant heat left over from the Big Bang.
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On this day in 1840 – July 1st – Robert Ball, Irish astronomer, lecturer and astronomy popularizer, was born in Dublin.

Ball was a university professor and the Royal Astronomer in Ireland. He was well known to the public for his books on astronomy, and for his public lectures. Between 1875 and 1910 he gave around 2500 lectures in towns and cities across Britain and Ireland.
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On this day in 1917 – July 1st – the 100" mirror for the Hooker telescope arrived at Mt Wilson Observatory.

The Hooker telescope was the biggest in the world for three decades. Edwin Hubble calculated the distance to Andromeda from a Cepheid variable he discovered there with the telescope. It showed Andromeda was a separate galaxy. Hubble and Milton Humason also observed the redshifts of a number of galaxies and found that they were moving away from us.
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On this day in 1985 – July 2nd – the European Space Agency (ESA) launched the Giotto probe to study Halley's Comet.

Giotto would be the first spacecraft ever to make close up observations of a comet.
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On this day in 1935 – July 3rd – geologist and Apollo 17 astronaut Harrison Schmitt was born in Santa Rita, New Mexico.

Schmitt is the only scientist to have walked on the Moon.
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On this day in 1054 – July 4th – Chinese astronomers observed the supernova explosion that created the Crab Nebula (Messier 1) in the constellation Taurus.

The supernova would have occurred some 6500 years before it was observed on Earth, since it's around 6500 light years away.
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On this day in 1868 – July 4th – American astronomer Henrietta Swan Leavitt was born in Lancaster, Massachusetts.

Her discovery of the relationship between the period and the luminosity of Cepheid variable stars made possible Edwin Hubble's work on galactic distances.
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On this day in 1997 – July 4th – NASA's Mars Pathfinder landed on Mars.

The robotic spacecraft consisted of a lander, renamed the Carl Sagan Memorial Station, and a wheeled robotic rover named Sojourner. It was the first successful Mars rover.
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On this day in 2005 – July 4th – NASA's Deep Impact probe collided with comet Tempel 1.

The Deep Impact mission was designed to study the interior composition of the comet Tempel 1 (9P/Tempel) by releasing an impactor into it.
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On this day in 2016 – July 5th – NASA's Juno spacecraft went into polar orbit around Jupiter.

The Juno mission is exploring Jupiter, seeking to unlock secrets of the giant planet and our solar system.
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On this day in 2003 – July 7th – NASA's Mars rover Opportunity was launched on a three-month mission.

Opportunity was still at work on the red planet until the summer of 2018 when it was unable to recover after a massive planetwide dust storm.
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On this day in 2011 – July 8th – space shuttle Atlantis was launched, the final space shuttle mission.

By the end of that mission, Atlantis, in its lifetime, had orbited the Earth a total of 4,848 times, traveling nearly 126,000,000 mi (203,000,000 km) – more than 525 times the distance from the Earth to the Moon.
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On this day in 1962 – July 10th – Telstar 1 was launched.

It was the beginning of a revolution in global communications.
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On this day in 1732 – July 11th – French astronomer Jérôme Lalande was born in Bourg-en-Bresse.

He held the chair of astronomy in the Collège de France in for nearly half a century and a number of his students became distinguished astronomers. As well as being an observer, Lalande also gave popular lectures and wrote about astronomy.
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On this day in 1979 – July 11th – NASA's Skylab re-entered the atmosphere.

Skylab had orbited for seven years and provided valuable data for human space flight.
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On this day in 2019 – July 13th – the Russian Spektr RG X-ray Observatory was launched.

The satellite is a Russian–German high-energy astrophysics space observatory.
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On this day in 1978 – July 14th – ESA's GEOS-2 satellite was launched on a Delta rocket from Cape Canaveral.

GEOS-2 was the first spacecraft dedicated completely to scientific measurements in an equatorial geostationary orbit.
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On this day in 2015 – July 14th – NASA's New Horizons mission made a historic fly-by of Pluto and its moons.

The data that came home revolutionized our conception of the dwarf planet and its family.
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On this day in 1943 – July 15th – Northern Irish astrophysicist Jocelyn Bell Burnell was born.

As a graduate student she first noted what turned out to be rotating neutron stars, now called pulsars. Until then, neutron stars were only theoretically an endpoint of the evolution of massive stars.
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On this day in 1965 – July 15th – NASA's Mariner 4 completed the first successful flyby of Mars.

Returning the first close-up pictures of the Martian surface, the Mariner 4 images were the first ever returned of another planet from deep space.
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On this day in 1967 – July 15th – the Apollo-Soyuz Test Project was launched from Baikonur Cosmodrome and the Kennedy Space Center.

This was the first joint U.S.-Soviet space flight, a symbol of detente between the superpowers - it involved the docking of an Apollo Command/Service Module with the Soviet Soyuz.
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On this day in 1969 – July 16th – Apollo 11 was launched.

Neil Armstrong, Buzz Aldrin and Michael Collins set off for the Moon. They weren't the first to visit our satellite, but Armstrong and Aldrin would be the first to land on it.
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On this day in 2000 – July 16th – NASA's Dawn spacecraft entered orbit around the asteroid Vesta.

The spacecraft later moved on to dwarf planet Ceres where it was active until November 2018.
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On this day in 1850 – July 17th – John Adams Whipple and William Cranch Bond took the first stellar photograph .

The photo was of the star Vega, taken at the Harvard College Observatory in the USA.
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On this day in 1894 – July 17th – Belgian priest, astronomer and physicist Georges Lemaître was born in Charleroi, Belgium.

Lemaître made the first definitive formulation of the idea of an expanding universe, and what was to become known as the Big Bang theory of the origin of the universe.
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On this day in 1921 – July 18th – NASA astronaut John Glenn was born in Cambridge, Ohio.

Glenn was the first American to orbit the Earth. He had a distinguished military career before becoming an astronaut, and was a US senator afterwards. In 1998 he took part in a space shuttle mission, making him oldest person ever to go into orbit.
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On this day in 1846 – July 19th – American astronomer Edward Pickering was born in Boston, Massachusetts.

Pickering was the director of Harvard College Observatory who hired women assistants (computers), and who modernized the observatory's work in astronomy by the use of photography.
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On this day in 1969 – July 20th – Apollo 11 astronauts became the first humans to set foot on another world.

Neil Armstrong, followed by Buzz Aldrin, stepped out of their lander and walked on the Moon, taking photographs, collecting rocks and setting up experiments.
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On this day in 1976 – July 20th – NASA's Viking 1 became the first spacecraft to land successfully on Mars and perform its mission.

Part of the mission was a biology experiment whose purpose was to look for evidence of life.
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On this day in 1620 – July 21st – French astronomer Jean Picard was born in La Flèche in the department of Sarthe.

Picard collaborated and corresponded with many fellow scientists, including Isaac Newton, Christiaan Huygens, Ole Rømer, and Giovanni Cassini, among others. He was a founding member of the French Academy of Sciences.
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On this day in 1784 – July 22nd – German astronomer and mathematician Friedrich Bessel was born in Minden.

Bessel was the first to publish a reliable value for the distance from the Sun to another star, by using parallax.
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On this day in 1928 – July 23rd – American astronomer Vera Rubin was born in Philadelphia, Pennsylvania.

Rubin's pioneering work on galaxy rotation rates uncovered a discrepancy between the predictions and the observations. This was early evidence for the existence of dark matter.
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On this day in 1972 – July 23rd – the USA launched Landsat 1.

The near-polar orbiting spacecraft served as a stabilized, Earth-oriented platform for obtaining information on Earth resources of all kinds, meteorology, pollution, etc. Over the lifetime of the satellite it provided around 300,000 images.
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On this day in 1950 – July 24th – the first rocket was launched from Cape Canaveral, Florida.

Cape Canaveral - which for a time was renamed Cape Kennedy - became the launch site for the manned space program. After the last space shuttle retired, the USA could only put astronauts into space via Russian launches. Then on November 15, 2020, a SpaceX Dragon was launched from Cape Canaveral with four astronauts.
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On this day in 1969 – July 24th – Apollo 11 returned safely to Earth.

President John F. Kennedy's goal "of landing a man on the moon and returning him safely to the earth before this decade is out" had been achieved, though he didn't live to see it.
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On this day in 1975 – July 24th – the last Apollo crew returned to Earth after docking and working with a Russian Soyuz crew.

The end of the Apollo Soyuz mission was the final flight of the Apollo program and the last US splashdown.
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On this day in 2009 – July 24th – the Gran Telescopio Canarias (GranTeCan or GTC) was dedicated.

Located on La Palma in the Canary Islands of Spain, it's the world's largest single-aperture optical telescope.
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On this day in 1982 – July 25th – Svetlana Savitskaya became the first woman to walk in space.

The Soviet cosmonaut was the first woman in space since Valentina Tereshkova's historic flight nineteen years earlier.
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On this day in 2000 – July 25th – the Zvezda Service Module docked with International Space Station.

It was the first fully Russian contribution to the International Space Station, and it served as the early cornerstone for the first human habitation of the station.
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On this day in 1609 – July 26th – English astronomer and mathematician Thomas Harriot looked at the Moon through a telescope, and made a dated sketch of what he saw.

It's the oldest known drawing of a telescopic body - it was made nearly four months before Galileo's first drawing.
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On this day in 1971 – July 26th – Apollo 15 was launched, crewed by Commander David Scott, Lunar Module Pilot James Irwin, and Command Module Pilot Alfred Worden.

This would be the first mission to use the lunar rover to explore the Moon.
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On this day in 1801 – July 27th – English mathematician and Astronomer Royal, Sir George Biddell Airy, was born in Alnwick, Northumberland.

He's known for his work on planetary orbits, measuring the mean density of the Earth and, in his role as Astronomer Royal, for establishing the meridian in Greenwich in London that became the prime meridian of the world.
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On this day in 1638 – July 28th – English polymath Robert Hooke, often called "England's Leonardo", was born in Freshwater, Isle of Wight.

Hooke contributed to astronomy, geology, structural engineering, microscopy, chemistry and physics, helped rebuild London after the Great Fire, and was a renowned experimenter, inventor, musician and artist.
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On this day in 1638 – July 28th – the first successful photographic image of a solar eclipse, showing the Sun's corona, was made.

The eclipse image was a daguerrotype made by J. Berkowski at the Royal Observatory in Königsberg, Germany (now Kaliningrad, Russia).
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On this day in 1919 – July 28th – the International Astronomical Union (IAU) was founded.

Its mission is to promote and safeguard the science of astronomy in all its aspects, including research, communication, education and development, through international cooperation.
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On this day in 1971 – July 31st – the first vehicle was driven on the Moon.

By using the lunar rover, astronauts Dave Scott and Jim Irwin were able to explore more widely than anyone had before.
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On this day in 1999 – July 31st – NASA's Lunar Prospector mission ended.

The probe investigated the Moon from low polar orbit, among other things mapping surface composition and possible polar ice deposits. The orbiter was deliberately crashed into a crater near the lunar south pole in the hope that it would create a plume in which water could be detected. (But it didn't.)
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On this day in 1786 – August 1st – German astronomer living in England, Caroline Herschel, discovered her first comet.

In the years from 1786 to 1797 she discovered eight comets.
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On this day in 1818 – August 1st – American astronomer Maria Mitchell was born in Nantucket, Massachusetts.

She was the first American woman to discover a comet, the first to become a college professor, and the first woman to be elected to scientific societies in the USA.
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On this day in 2004 – August 3rd– NASA launched the MESSENGER spacecraft to Mercury.

MESSENGER's mission was to study Mercury's chemical composition, geology, and magnetic field.
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On this day in 2007 – August 4th – the Phoenix Mars Lander was launched.

The program was a partnership of universities in several countries directed by NASA's Jet Propulsion Laboratory. Its purpose was to look for environments suitable for microbial life on Mars.
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On this day in 2011 – August 4th – NASA's Juno mission to Jupiter was launched.

Now in its extended mission, Juno will continue its investigation of the solar system's largest planet through September 2025, or until the spacecraft's end of life.
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On this day in 1930 – August 5th – Neil Armstrong was born in Wapakoneta, Ohio, USA.

Armstrong, Apollo 11 astronaut, was the first human to set foot on another world when he stepped onto the Moon at 02:56 GMT on 21 July 1969.
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On this day in 1961 – August 6th – the Soviet Vostok 2 was launched, the first full day mission.

Cosmonaut Gherman Titov became the second man in space and the first person to sleep in space.
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On this day in 2012 – August 6th – the Mars Science Laboratory rover Curiosity landed on Mars.

Curiosity continues to carry out the mission of searching for signs of habitable environments, past and present, on the red planet.
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On this day in 2014 – August 6th – ESA's Rosetta became the first spacecraft to rendezvous with a comet.

Rosetta finally met up with Comet 67P/Churyumov-Gerasimenko after a decade-long journey chasing it.
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On this day in 1576 – August 8th – Tycho Brahe laid the cornerstone for Uraniborg.

Uraniborg, built on the island of Hven between Denmark and Sweden, was a custom-built observatory and research center, the most advanced that had ever been seen at that time.
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On this day in 1948 – August 8th – Soviet cosmonaut Svetlana Savitskaya was born in Moscow.

She was the second woman in space and the first to carry out a spacewalk.
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On this day in 1989 – August 8th – the European Space Agency (ESA) satellite Hipparcos was launched.

It was the first space experiment devoted to the accurate measurement of the positions of celestial objects in the sky. It operated until 1993.
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On this day in 2001 – August 8th – NASA's Genesis spacecraft was launched.

Genesis was a sample-return probe designed to collect a sample of solar wind and return it to Earth for analysis.
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On this day in 2000 – August 9th – the European Space Agency (ESA) launched the second pair of Cluster satellites.

This completed the four-satellite constellation of the Cluster II mission. The four spacecraft are providing a detailed three-dimensional map of the magnetosphere.
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On this day in 1675 – August 10th – the first Astronomer Royal, John Flamsteed, laid the cornerstone for the Royal Observatory in Greenwich.

By the end of the 19th century most of the world's shipping was using navigation charts based on the Prime Meridian at Greenwich.
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On this day in 1966 – August 10th – NASA's Lunar Orbiter 1 was launched.

It was the first US spacecraft to orbit the Moon.
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On this day in 1990 – August 10th – NASA's Magellan spacecraft entered orbit around Venus to begin radar mapping the surface.

Magellan had been launched on May 4, 1989. It was the first interplanetary mission to be launched from a Space Shuttle.
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On this day in 1877 – August 12th – American astronomer Asaph Hall discovered Deimos, moon of Mars.

Moons had long before been found for all the other planets beyond Earth, so Hall's discovery was quite a sensation.
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On this day in 1919 – August 12th – Anglo-American astronomer Margaret Burbidge (nee Peachey) was born in Cheshire, England.

She made notable contributions to the theory of quasars, and to measurements of the rotation and masses of galaxies. Burbidge was also the lead author on a groundbreaking paper describing how chemical elements are formed in the depths of stars through nuclear fusion. She was the first woman director of the Royal Greenwich Observatory and the first woman to be president of the American Astronomical Society.
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On this day in 1964 – August 12th – the Soviet craft Voskhod 1 was launched.

As the first spacecraft to carry three people, it was another step forward in manned space flight.
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On this day in 2018 – August 12th – NASA's Parker Solar Probe (PSP) was launched.

Its mission is to observe and probe the Sun's outer corona. At closest approach, Parker Solar Probe will be hurtling around the Sun at approximately 430,000 miles per hour! That's fast enough to get from Philadelphia to Washington, D.C., in one second.
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On this day in 1936 – August 17th – American software engineer Margaret Hamilton was born in Paoli, Indiana.

Hamilton was the lead developer for the Apollo flight software, and her rigorous systems approach was essential to its success.
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On this day in 1970 – August 17th – the Soviet probe Venera 7 was launched.

When it landed on the Venusian surface, it became the first spacecraft both to land on another planet and to transmit data from there back to Earth.
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On this day in 2006 – August 17th – Voyager 1 was the first spacecraft to get 100 AU from the Earth.

The spacecraft went on to become the first craft to leave the heliosphere, the bubble that the solar wind makes in space.
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On this day in 1868 – August 18th – during a total solar eclipse, French astronomer Pierre Janssen observed an unknown line in the spectrum of the Sun, which turned out to be a new element, helium.

The same result was found independently by British astronomer Norman Lockyer, and both Janssen's and Lockyer's communications were presented to the French Academy of Sciences on October 26, 1868.
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On this day in 1646 – August 19th – English astronomer John Flamsteed was born in Denby, Derbyshire.

Flamsteed was the first Astronomer Royal at the Royal Observatory Greenwich, and his star atlas was the standard for a nearly a century.
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On this day in 1891 – August 19th – American astronomer Milton Humason was born in Dodge Center, Minnesota.

Humason's careful measurement of the radial velocities of several hundred galaxies underpinned the work of Edwin Hubble.
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On this day in 1982 – August 19th – Soviet cosmonaut Svetlana Savitskaya became the second woman to go into space.

Her flight on the Soyuz T-7 took place 19 years after that of the first woman in space, Valentina Tereshkova.
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On this day in 1975 – August 20th – NASA's Viking 1 was launched. (It was followed three weeks later by Viking 2).

A year after the launch it became the first spacecraft to land successfully on Mars and perform its mission.
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On this day in 1976 – August 22nd – the Soviet Luna 24 mission returned soil samples from the Moon.

These samples were different from the previous sample return missions because they were collected from 2.5 meters below the surface.
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On this day in 1966 – August 23rd – NASA's Lunar Orbiter 1 took the first picture of the Earth ever taken from the Moon.

The spacecraft's primary mission was to photograph smooth areas of the lunar surface for selection and verification of safe landing sites for the Surveyor and Apollo missions.
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On this day in 2006 – August 23rd – a vote by the General Assembly of the International Astronomical Union changed the classification of Pluto from planet to the new category of dwarf planet.

Two of the reasons for the reclassification were Pluto's small size (smaller than the Moon) and its highly elliptical tilted orbit which overlaps with that of Neptune.
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On this day in 1609 – August 25th – Galileo Galilei made the first recorded demonstration of a telescope.

He demonstrated to Venetian lawmakers a telescope he had made - it had a magnification about 8 or 9.
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On this day in 1989 – August 25th – NASA's Voyager 2 spacecraft flew past Neptune.

Voyager 2 is still the only spacecraft to have visited Neptune.
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On this day in 2003 – August 25th – NASA's Spitzer Space Telescope was launched.

Spitzer was an infrared telescope whose mission ended on January 30, 2020.
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On this day in 1918 – August 26th – Katherine Coleman Goble Johnson was born in White Sulphur Springs, West Virginia.

Katherine Johnson was an African-American mathematician whose calculations of orbital mechanics as a NASA employee were important for the success of the first and subsequent U.S. manned spaceflights.
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On this day in 1962 – August 27th – NASA's Mariner 2 spacecraft was launched.

This probe to Venus was the first robotic space probe to conduct a successful planetary encounter.
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On this day in 1789 – August 28th – William Herschel discovered Enceladus, a moon of Saturn.
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On this day in 1993 – August 28th – NASA's Galileo spacecraft did a flyby of asteroid Ida.

Galileo was an unmanned spacecraft that probed the planet Jupiter and its moons, as well as some other Solar System objects on its way to the Jovian system
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On this day in 1745 – August 30th – German astronomer Johann Hieronymus Schröter was born in Erfurt, Germany.

He built his own observatory and devoted himself primarily to solar and planetary astronomy. His two volumes on lunar topography reached levels of detail that were to remain unsurpassed for many years.
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On this day in 1913 – August 31st – English radio astronomer Bernard Lovell was born in Oldland Common, Gloucestershire.

Lovell was a pioneer of radio astronomy and founded the Jodrell Bank Observatory in Cheshire, England in 1945. When the telescope was built there - later named the Lovell Telescope - it was for many years the largest steerable radio telescope in the world.
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On this day in 1979 – September 1st – NASA's probe Pioneer 11 became the first spacecraft to fly past Saturn.

Pioneer 11 is now nearly nearly 112 times farther from the Sun than Earth is - the spacecraft's final signal was received in 2003.
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On this day in 1970 – September 3rd – NASA cancelled the last two planned lunar landings.

Apollo 18 and Apollo 19 were officially cancelled following cuts to NASA's budget for 1971. The Cold War political point had been made and the public had also lost interest after the excitement of Apollo 11.
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On this day in 2006 – September 3rd – ESA's SMART-1 spacecraft ended its mission when it was deliberately crashed into the Moon's surface.

SMART-1 spent 16 months testing testing innovative and miniaturised space technologies. It also produced detailed maps of the Moon's chemical make-up, to help refine theories about its birth.
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On this day in 1908 – September 5th – Edoardo Amaldi, cosmic-ray physicist, was born in Carpaneto Piacentino, Italy.

The reconstruction of the Italian scientific environment after World War II was due almost entirely to Amaldi, and he was one of the founding fathers of the European Space Research Organisation which would later become the European Space Agency (ESA).
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On this day in 1977 – September 5th – NASA launched the Voyager 1 spacecraft.

Voyager 1 is now almost 161 AU from Earth - that's 161 times farther from us than we are to the Sun. It's in interstellar space.
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On this day in 2008 – September 5th – ESA's Rosetta Mission made its closest approach to asteroid (2867) Steins at a distance of 800 km.

This was Rosetta's first encounter with an asteroid and it produced data about the asteroid that couldn't have been obtained from Earth.
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On this day in 2013 – September 7th – NASA launched the Lunar Atmosphere and Dust Environment Explorer (LADEE).

The orbiter explored the lunar exosphere and dust in the Moon's vicinity.
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On this day in 2004 – September 8th – The orbiter explored the lunar exosphere and dust in the Moon's vicinity.

Some samples were salvaged, as some of the contamination could be dealt with. The mission's major science objectives were achieved.
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On this day in 2016 – September 8th – NASA launched OSIRIS-REx, an asteroid study and sample return mission.

The spacecraft arrived at asteroid Bennu in December 2018, carried out detailed reconnaissance of the asteroid and collected samples. It's expected to return the sample capsule to Sept. 24, 2023 as main spacecraft journeys on to asteroid Apophis for a 2029 rendezvous.
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On this day in 1787 – September 9th – American astronomer William Cranch Bond was born.

Bond was the first director of the Harvard College Observatory, and a pioneer of astrophotography.
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On this day in 1857 – September 9th – American astronomer James Keeler was born in La Salle, Illinois.

Keeler was the director of the University of Pittsburgh's Allegheny Observatory in 1891, and later of the Lick Observatory in California. Among other things, he was known for his studies of the rings of Saturn, confirming that Saturn’s ring system is not a solid unit, and for expanding astronomers' understanding of nebulae through an extended series of photographs using a large telescope.
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On this day in 2011 – September 10th – NASA launched the two small spacecraft GRAIL A (Ebb) and GRAIL B (Flow).

The Gravity Recovery and Interior Laboratory (GRAIL) mapped the gravitational field of the Moon in unprecedented detail.
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On this day in 1975 – September 9th – NASA launched the Viking 2 mission.

It was an orbiter and lander like Viking 1, the other half of the first astrobiology mission to Mars
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On this day in 1717 – September 11th – Swedish astronomer Pehr Wilhelm Wargentin was born in Sunne, Sweden.

He was the first director of the Stockholm Observatory, and is probably best remembered today for his extensive study and observation of Jupiter’s satellites.
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On this day in 1877 – September 11th – English astrophysicist and mathematician James Jeans was born in Ormskirk, Lancashire.

Jeans made major contributions to the early understanding of stellar radiation and stellar evolution.
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On this day in 1985 – September 11th – the International Cometary Explorer (ICE) became the first spacecraft to make a flyby of a comet.

It passed through the plasma tail of comet Giacobini-Zinner within about 7,800 km (4,800 mi) of the nucleus.
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On this day in 1997 – September 11th – NASA's Mars Global Surveyor arrived at Mars.

It is a global mapping mission, carrying a suite of science instruments designed to study the entire Martian surface, atmosphere and interior.
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On this day in 1959 – September 12th – the Soviet spacecraft Luna 2 was launched to the Moon.

The following day, Luna 2 became the first human object to land on another celestial body.
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On this day in 1970 – September 12th – the Soviet spacecraft Luna 16 was launched to the Moon.

It was the first robotic probe to land on the Moon and return a sample of lunar soil to Earth.
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On this day in 1915 – September 14th – John Lowry Dobson was born in Beijing, China.

The American amateur astronomer, who grew up in the San Francisco area, was a popularizer of astronomy. He's best known for having designed and promoted a quality telescope that could be made using inexpensive, readily available materials. The Dobsonian telescope meant that amateur astronomers could afford a portable instrument of a size and aperture that would otherwise be beyond their means.
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On this day in 1938 – September 15th – American astronomer James Christy was born in Milwaukee, Wisconsin.

Christy is best known for his discovery of Charon, the first known moon of Pluto and the largest of its five known natural satellites.
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On this day in 1968 – September 15th – the Soviet spacecraft Zond 5 was launched.

It was the first spacecraft to travel to the Moon with living creatures on board. It circled the Moon and returned safely to Earth with its passengers, including two tortoises.
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On this day in 2017 – September 15th – the NASA/ESA Cassini mission ended with planned entry into Saturn's atmosphere.

The Cassini spacecraft had spent over 13 years studying Saturn and its moons and rings.
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On this day in 1848– September 16th – Saturn's moon Hyperion was discovered.

American astronomers William and George Bond, and English astronomer William Lassell independently discovered the moon.
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On this day in 1764 – September 17th – English astronomer John Goodricke was born in Groningen in the Netherlands.

An infection as an infant rendered him deaf and mute. However he overcame the handicaps and became a highly proficient astronomical observer and pioneering investigator of variable stars. He theorized that the variable star Algol was a binary star whose variability was due to a dark companion periodically eclipsing it.
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On this day in 1789 – September 17th – William Herschel discovered Saturn's moon Mimas.

The huge crater in the leading hemisphere of Mimas is named Herschel in honor of the moon's discoverer.
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On this day in 1857 – September 17th – Russian rocket scientist Konstantin Tsiolkovsky was born in Izhevskoye, Russia.

Tsiolkovsky is considered one of the founding fathers of rocketry and astronautics. Long before the Wright brothers' first plane flew 120 feet, he was thinking space travel. And when it was still science fiction to most people, he was developing the theory, and doing the math, for multistage rockets.
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On this day in 1930 – September 17th – NASA astronaut Edgar Dean "Ed" Mitchell was born in Hereford, Texas.

Mitchell was the lunar module pilot for the Apollo 14 mission and the sixth man to walk on the Moon.
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On this day in 1977 – September 18th – NASA's Voyager 1 took the first ever photo of both the Earth and the Moon together in space.

The crescent Moon is very faint in the upper left of the photo.
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On this day in 2006 – September 18th – Anousheh Ansari was the first self-funded woman to travel to the International Space Station.

Ansari is an Iranian American engineer and co-founder and chairwoman of Prodea Systems. During her eight-day stay aboard the International Space Station, she conducted several experiments for the European Space Agency. Ansari also published a weblog, something that had not been done before.
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On this day in 1886 – September 21st – English writer H.G. Wells was born in Bromley, Kent.

Wells is considered to be one of the fathers of science fiction. His best known novel is The War of the Worlds.
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On this day in 1969 – September 21st – during a comet-hunting expedition, Klim Churyumov and Svetlana Gerasimenko discovered the object subsequently named Comet 67P/Churyumov-Gerasimenko.

This was the comet that would later be orbited and studied by ESA's Rosetta Mission.
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On this day in 2003 – September 21st – NASA's Galileo mission was ended by having the spacecraft plunge into Jupiter.

Galileo was the first spacecraft to orbit Jupiter, the first to achieve an asteroid flyby (951 Gaspra), and it discovered the first asteroid moon - Dactyl, orbiting asteroid 243 Ida.
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On this day in 1556 – September 22nd – a Danish noblewoman and horticulturalist, Sophia Brahe was born in Knudstrop, Denmark (now part of Sweden).

She was also knowledgable in astronomy, chemistry and medicine. The younger sister of Tycho Brahe, she often assisted him with his astronomical observations.
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On this day in 2006 – September 22nd – the solar mission Hinode was launched.

Hinode [Sunrise] is a Japanese solar mission with USA and UK collaboration. It was planned as a three-year mission to explore the magnetic fields of the Sun, but is still collecting data.
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On this day in 2014 – September 22nd –NASA's MAVEN mission went into orbit around Mars.

MAVEN (Mars Atmosphere and Volatile EvolutioN) is studying the Martian atmosphere.
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On this day in 1783 – September 23rd – Caroline Herschel discovered NGC 253, the Sculptor Galaxy.

Also known as the Silver Coin or Silver Dollar Galaxy, NGC 253 is a starburst spiral galaxy in the constellation Sculptor.
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On this day in 1846 – September 23rd –Neptune was discovered by Johann Galle and his colleague Heinrich Louis d’Arrest at the Berlin Observatory.

Galle had received calculations from Urbain LeVerrier which showed where there might be a new planet, and they found the planet that very night. Eventually, it was named Neptune after the Roman sea god.
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On this day in 1930 – September 24th – John Young was born in San Francisco, California.

Young had a varied and distinguished career, which in 1972, included being the Commander of Apollo 16 and the ninth person to walk on the Moon..

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On this day in 2014 – September 24th – the Indian Space Research Organisation (ISRO)'s Mars Orbiter Mission (MOM) entered Mars orbit.

MOM was India's first interplanetary mission. On October 4, 2022, it was declared that the Mars Orbiter Mission "had attained its end-of-life"..
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On this day in 1634 – September 25th – Danish astronomer Ole Christensen Rømer was born in Aarhus.

He is best known for making the first quantitative measurements of the speed of light by precisely measuring the length of time between eclipses of Jupiter by one of its moons..
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On this day in 1814 – September 27th – American astronomer Daniel Kirkwood was born in Harford County, Maryland.

Kirkwood is best known for his study of asteroid orbits. When arranging the then-growing number of discovered asteroids by their distance from the Sun, he noted several gaps, now named Kirkwood gaps. He associated these gaps with orbital resonances with the orbit of Jupiter..
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On this day in 2007 – September 27th – NASA's Dawn spacecraft was launched.

Dawn orbited and studied the asteroid Vesta, and then went on to study dwarf planet Ceres. The mission has ended, but the spacecraft remains in orbit around Ceres..

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On this day in 1605 – September 28th – French astronomer and mathematician Ismaël Bullialdus was born in Loudon.

Often regarded as ‘the most noted astronomer of his generation’ he wrote several books, the most famous being Astronomia Philolaica, in which he supported Johannes Kepler’s elliptical planetary orbits. Bullialdus was also a defender of the views and ideas of Copernicus and Galileo.
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On this day in 1765 – September 29th – German astronomer Karl Ludwig Harding was born in Lauenburg.

He is best remembered for discovering the third asteroid, Juno. He found it on 1 Sep 1804 while working at the private observatory of his countryman and fellow astronomer, Johann Hieronymus Schröter..

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On this day in 1880 – September 30th – Henry Draper took the first photograph of a nebula, the Orion Nebula.

Draper was an American physician, professor of medicine, keen astronomer and pioneer of astrophotography. Stars with HD numbers are listed in the Henry Draper Catalog compiled by Harvard College Observatory and funded by Draper's widow, Anna Draper.
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On this day in 2016 – September 30th – ESA's Rosetta mission ended with a controlled descent to the surface of Comet Churyumov-Gerasimenko.
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On this day in 1891 – September 30th – Soviet scientist, mathematician, astronomer and geophysicist Otto Yulyevich Schmidt was born in Mogilev, Russian Empire (now Belarus).

A graduate of Kiev University in 1913, Schmidt was to become professor of geophysics at the Institute of Earth Physics in Moscow where he specialized in the study of lunar surface.
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On this day in 1845 – October 1st – English astronomer William Henry Mahoney Christie was born in Woolwich, London.

He served as Chief Assistant to George Biddell Airy at the Royal Observatory, Greenwich from 1870 to 1881, replacing Airy in 1881 to become the eighth Astronomer Royal of England. He remained in office until his retirement from the post in 1910.
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On this day in 1897 – October 1st – the 40-inch refracting telescope was dedicated at Yerkes Observatory in Williams Bay, Wisconsin, USA.

From 1897-1909 it was the world's largest telescope. It's still the world's largest refracting telescope, and is commonly known as the Yerkes "Great Refractor".
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On this day in 1958 – October 1st – NASA was founded.
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On this day in 1935 – October 3rd – Apollo 16 astronaut Charles "Charlie" Duke was born in Charlotte, North Carolina.

Duke was the Lunar Module Pilot of Apollo 16 and the tenth and youngest person to walk upon the surface of the Moon.
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On this day in 1957 – October 4th – the Soviet Union launched Sputnik 1.

Sputnik was the world's first successful artificial satellite.
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On this day in 1959 – October 4th – the Soviet Union launched Luna 3.

The spacecraft captured humanity's first-ever view of the far side of the Moon.
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On this day in 1882 – October 5th – Robert Goddard was born in Worcester, Massachusetts.

Goddard was an American engineer, professor, physicist, and inventor who is credited with creating and building the world's first liquid-fuelled rocket. Although he received little public support in his lifetime, he's now considered one of the founding fathers of modern rocketry.
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On this day in 1923 – October 5th – Edwin Hubble discovered a Cepheid variable in M31 (the Andromeda Galaxy).

Cepheid variable stars, based on the work of Henrietta Leavitt, can be used as distance indicators. Hubble was able to show that M31 was too far away to be an object in our own Galaxy.
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On this day in 1962 – October 5th – the European Southern Observatory (ESO) was founded.

It's a highly productive astronomical observatory, providing state-of-the-art research facilities to astronomers and astrophysicists of many countries.
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On this day in 1732 – October 6th – English astronomer Nevil Maskelyne was born in London.

He was the fifth Astronomer Royal of England, and he held the post for 46 years. Maskelyne founded the Nautical Almanac and Astronomical Ephemeris, the first nautical almanac to contain data dedicated to the convenient determination of longitude at sea.
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On this day in 1990 – October 6th – the joint ESA/NASA deep-space mission Ulysses was launched by the Space Shuttle Discovery.

Its elliptical heliocentric operational orbit took it high above the ecliptic plane to allow the charting of the unknown reaches of space above and below the poles of the Sun.
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On this day in 1995 – October 6th – The Swiss team of Michel Mayor and Didier Queloz made the stunning announcement of the first detection of a planet orbiting a star like our Sun.

The planet found by Mayor and Queloz, 51 Pegasi b, is a is “hot Jupiter” that takes only four days to complete one orbit. We know of many hot Jupiters now, but it was a sensation at the time.
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On this day in 1995 – October 7th – Niels Bohr was born in Copenhagen, Denmark.

Bohr was the the physicist who made foundational contributions to understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922.
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On this day in 1873 – October 8th – Danish chemist and astronomer Ejnar Hertzsprung was born in Copenhagen, Denmark.

The Hertzsprung-Russell diagram is a classification system for explaining stellar types and stellar evolution. Hertzsprung and American astronomer Henry Norris Russell independently made the discoveries that created the diagram.
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October 1604 – a supernova appeared that has been associated with Johannes Kepler who observed and documented it.

Kepler's supernova occurred about 20,000 light years away in the constellation Ophiuchus. It was so bright that at its peak it was visible during the day for over three weeks.
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On this day in 1873 – October 9th – German physicist and astronomer Karl Schwarzschild was born in Potsdam.

Although his best known research relates to general relativity, Schwarzschild worked on a wide range of subjects including celestial mechanics quantum mechanics, spectroscopy and instrumental astronomy.
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On this day in 1846 – October 10th – English businessman and amateur astronomer William Lassell discovered Triton, Neptune's largest moon.

Lassell discovered the moon just 17 days after German astronomer Johann Galle discovered Neptune, using Urbain LeVerrier's calculations.
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On this day in 1980 – October 10th – the Very Large Array (VLA) was dedicated.

Now known as the Karl G. Janksy Array, it's a prominent radio telescope facility in New Mexico. Jansky was a pioneer of radio astronomy.
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On this day in 1758 – October 11th – German physician and astronomer Heinrich Olbers was born in Hemelingen, Bremen.

Olbers's major discoveries were the asteroids Pallas and Vesta.
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On this day in 1964 – October 12th – the Soviet craft Voskhod 1 was launched.

As the first spacecraft to carry three cosmonauts, this was an advance in manned space flight.
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On this day in 1884 – October 13th – Greenwich in the United Kingdom was adopted as the prime meridian of the world.

There had been many prime meridians in use by countries around the world. But at the International Meridian Conference held in Washington DC, 25 maritime countries voted to adopt the Greenwich meridian as the longitude line of zero degrees.
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On this day in 1993 – October 13th – the British Interplanetary Society was founded in Liverpool, UK by Phillip Cleator.

The society is the oldest space advocacy organisation in the world.
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On this day in 1994 – October 13th – NASA's Magellan mission ended by plunging the spacecraft into Venus.

Magellan - also referred to as the Venus Radar Mapper - was the first interplanetary mission to be launched from the Space Shuttle. It mapped the surface of Venus and measured the planetary gravitational field.
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On this day in 1788 – October 14th – Irish geophysicist, explorer and astronomer Edward Sabine was born in Dublin.

He's best remembered by astronomers for his research into changes in the Earth’s magnetic field, which he eventually recognised as being associated with solar activity. Using pendulum experiments, Sabine also made what was the most accurate determination of the exact shape of the Earth up to that time.
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On this day in 1785 – October 15th – English astronomer James South was born in Southwark, London.

South was an active observer, best remembered for his observation of double stars. He and John Herschel compiled a catalog of the double stars originally observed by William Herschel, and South went on to observe a further 458 double stars. He was awarded both the Gold Medal of the Royal Astronomical Society and the prestigious Copley Medal of the Royal Society.
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On this day in 1829 – October 15th – American astronomer Asaph Hall was born in Goshen, Connecticut.

Hall is best known for his discovery of Phobos and Deimos, the moons of Mars.
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On this day in 1987 – October 15th – the NASA/ESA Cassini-Huygens mission was launched to study the Saturnian system.

The spacecraft arrived at Saturn in January 2005 and studied the system for nearly twenty years.
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On this day in 2003 – October 15th – China launched Shenzhou 5.

Shenzhou 5 was China's first manned spaceflight, with Yang Liwei as China's first taikonaut (astronaut).
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On this day in 1956 – October 17th – Mae Jemison was born in Decatur, Alabama.

Jemison was the first black woman to travel into space when she served as a mission specialist aboard the Space Shuttle Endeavour. She has also been an engineer, a trained dancer, a doctor, a university professor and a businesswoman.
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On this day in 2006 – October 17th – the European Space Agency (ESA) launched the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL).

For six years it was the most sensitive gamma ray observatory ever, and it continues its operations in detecting some of the most energetic radiation coming from space.
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On this day in 1967 – October 18th – the Soviet probe Venera 4 was the first to send measurements from the atmosphere of another planet.

It was hoped that the probe would make a soft landing on Venus, but contact was lost when it was about 25 km above the surface.
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On this day in 1910 – October 19th – Indian-American astrophysicist and Nobel laureate Subrahmanyan Chandrasekhar was born in Lahore (now part of Pakistan).

A Nobel laureate, he's known for his work on stellar evolution, including black holes. The Chandrasekhar Limit is the dividing line between the mass of a star that has spent its nuclear fuel and will collapse into a white dwarf and one massive enough to go out with a bang - a supernova. It's about 1.4 times the Sun's mass.
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On this day in 2006 – October 19th – MetOp-A, Europe's first meteorological satellite in polar orbit, was launched.

Metop-A was in operation for 15 years, three times longer than expected.
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On this day in 2016 – October 19th – the European Space Agency's ExoMars mission arrived at Mars.

There were two parts to the mission. The Trace Gas Orbiter (TGO) was successfully inserted into orbit and is working as expected. However due to a systems malfunction, the experimental lander Schiaparelli crashlanded on Mars.
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On this day in 1923 – October 21st – the Deutsches Museum in Munich, Germany presented the world's first public planetarium show.

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On this day in 2008 – October 21st – India's space agency, ISRO, launched the Chandrayaan-1 lunar probe.

It was India's first satellite to leave Earth orbit, and the mission also included the first Indian deep space radio communications antenna.
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On this day in 1905 – October 22nd – American physicist and radio engineer Karl Jansky was born in Norman, Oklahoma Territory.

In August 1931 Jansky was the first to discover radio waves of extraterrestrial origin. He's considered one of the founding figures of radio astronomy.
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On this day in 1975 – October 22nd – the Soviet Union's Venera 9 probe went into orbit around Venus.

The mission included an orbiter - the first to orbit another planet - and a lander, which was the first to return images from the surface of another planet.
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On this day in 1969 – October 23rd – the discoverers of comet 67P/Churyumov-Gerasimenko announced their discovery to the Central International Bureau of Astronomical Telegrams.

ESA's Rosetta spacecraft and the lander Philae lie on the comet - they spent two years studying it.
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On this day in 1851 – October 24th – English astronomer William Lassell discovered two moons of Uranus, Umbriel and Ariel.
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On this day in 1946 – October 24th – the first photograph of Earth was taken from space.

The photo was taken from a rocket 105 km above the ground; it had been launched from the White Sands Missile Range in New Mexico, USA.
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On this day in 1998 – October 24th – NASA's Deep Space 1 spacecraft was launched.

It would go on to test advanced technologies and make a flyby of asteroid 9969 Braille and of comet 19P/Borrelly.
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On this day in 2001 – October 24th – NASA's Mars Odyssey was inserted into Martian orbit. It's the longest-surviving continually active spacecraft orbiting a planet other than Earth.

From orbit, it's looking for evidence of past or present water and ice, as well as studying the planet's geology and radiation environment. It also assisted the Curiosity rover as a relay.
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On this day in 1671 – October 25th – Italian-French astronomer Giovanni Cassini discovered Iapetus, one of Saturn's moons.

Iapetus is the third largest and one of the stranger of the many moons of Saturn.
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On this day in 1789 – October 25th – German astronomer Samuel Heinrich Schwabe was born in Dessau, Anhalt.

He is best known for his work on sunspots and the discovery of the 11-year sunspot cycle.
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On this day in 1887 – October 25th – American astronomer Henry Norris Russell was born in Oyster Bay, New York.

Russell was one of the major figures of early 20th century astronomy. He's best known today for his part in creating what's now called the Hertzsprung-Russell diagram which demonstrates stellar evolution. (Danish astronomer Ejnar Hertzsprung independently made the same discovery.)
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On this day in 2006 – October 25th – NASA launched STEREO.

STEREO was a solar observation mission using two identical spacecraft in two slightly different orbits. That permitted stereoscopic imaging of the Sun. The mission lasted longer than the two years for which it was planned, but in 2014 STEREO-B malfunctioned and couldn't be recovered. STEREO-A is still operational.
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On this day in 1902 – October 26th – American astronomer Henrietta Hill Swope was born in St. Louis, Missouri.

She is best known for her work on variable stars, especially the study of Cepheid variables which can be used to measure the distances to other galaxies.
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On this day in 1961 – October 27th – the first Saturn space launch vehicle was launched from Cape Canaveral, Florida.

This was the first mission of the Apollo program - the Saturn V eventually took astronauts to the Moon.
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On this day in 1971 – October 28th – the United Kingdom became the sixth nation to launch a satellite.

The Prospero satellite, the only satellite launched by a British rocket, carried a series of experiments to investigate the effects of the space environment.
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On this day in 1728 – October 30th – Polish-Lithuanian astronomer and mathematician Martin Poczobutt was born in Salomenka, Lithuania.

For over forty years, he was the director of the Vilnius Astronomical Observatory. The huge number of astronomical observations carried out by Poczobut includes those of comets and asteroids, the orbital motions of Mercury, and several solar and lunar eclipses.
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On this day in 1930 – October 31st – Apollo astronaut Michael Collins was born in Rome, Italy.

Collins, a former Air Force test pilot, was the Command Module Pilot for the Apollo 11 mission.
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On this day in 2005 – October 31st – the Hubble Space Telescope discovery of two new moons of Pluto was announced.

The moons were later named Nix and Hydra. Nyx is the goddess of the night and mother of Charon. Hydra was a giant guardian serpent with nine heads.
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On this day in 1919 – November 1st – Anglo-Austrian mathematician and cosmologist Hermann Bondi was born in Vienna, Austria.

Bondi was a distinguished academic and Fellow of the Royal Society. Among many positions outside academia, from 1967-1971, he served as Director-General of the European Space Research Organisation (ESRO) which later became the European Space Agency (ESA).
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On this day in 1885 – November 2nd – American astronomer Harlow Shapley was born in Nashville, Missouri.

Shapley was the director of the Harvard College Observatory for thirty years, and he was known as an expert in his main area of study, the Milky Way.
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On this day in 1917 – November 2nd – the 100-inch telescope on Mount Wilson saw first light. It was the largest telescope in the world for over thirty years.

Using observations he made on the telescope in 1922–1923, Edwin Hubble produced two fundamental results that changed the scientific view of the Universe.
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On this day in 2000 – November 2nd – Expedition 1 arrived at the International Space Station (ISS).

The ISS has been continuously occupied ever since then. As of May 2023, a total of 269 individuals from 21 countries had travelled to the ISS, some more than once.
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On this day in 1957 – November 3rd – Sputnik 2 carried the dog Laika into space.

Laika was the first living creature to be sent into Earth orbit. Sadly, she didn't survive it.
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On this day in 1871 – November 4th – American astronomer William Hammond Wright was born in San Francisco, California.

Among his accomplishments was the research he carried out into the radial velocity of stars in the southern sky. This was mainly done at the Chile station of California's Lick Observatory. He later became the director of Lick Observatory, a post he held from 1935-1942.
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On this day in 2013 – November 5th – the Indian Space Research Organisation (ISRO) launched the Mars Orbiter Mission (MOM).

MOM - also called Mangalyaan ("Mars-craft" in Sanskrit) was India's first interplanetary mission. It completed over seven years in orbit, but in 2022, it was irrevocably damaged during a period of lost communications.
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On this day in 2018 – November 5th – Voyager 2 entered interstellar space.

It was the second spacecraft to cross the heliopause. The heliopause is the region where the tenuous hot solar wind meets the cold dense interstellar medium. Voyager 1 crossed this boundary in 2012.
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On this day in 1572 – November 6th – Tycho Brahe recorded his observation of a bright new star (now listed as supernova SN 1572) in the constellation Cassiopeia.

The understanding of the time was that the stars were part of a sphere which was perfect and unchangeable, so the new object was assumed to be a local phenomenon. However, Tycho's study showed that it was a distant object.
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On this day in 1631 – November 7th – French priest and astronomer Pierre Gassendi observed a Transit of Mercury

Johannes Kepler had predicted transits of Mercury and Venus, but when Gassendi witnessed a transit of Mercury, he was the first person to see such a transit. The last transit of Mercury was in November 2019, but the next one won't occur until November 13, 2032.
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On this day in 1656 – November 8th – English astronomer (and master of several other sciences) Edmond Halley was born in Haggerston which is now part of the London Borough of Hackney.

Halley was one of the greatest minds of his era. He is still known today for Halley's Comet, which bears his name after he correctly predicted its return.
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On this day in 1934 – November 9th – American astronomer Carl Sagan was born in Brooklyn, New York.

Sagan was also noted as a science writer and communicator, and is still remembered by many for his television series Cosmos. In 2009 Carl Sagan Day was initiated as an annual celebration of astronomy and of Sagan's ideals.
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On this day in 1967 – November 9th – a Saturn V launch vehicle took the unmanned Apollo 4 into space.

It was the first test of the Saturn V rocket, which would be used by the U.S. Apollo program to send astronauts to the Moon.
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On this day in 2005 – November 9th – the European Space Agency (ESA) launched Venus Express.

Its main objective was the long term observation of the Venusian atmosphere. The spacecraft observed it for nearly nine years.
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On this day in 1861 – November 10th – Scottish astronomer Robert T. A. Innes was born in Edinburgh.

Innes is best known for his discovery of Proxima Centauri, the closest star to Earth after the Sun.
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On this day in 1875 – November 11th – American astronomer Vesto Slipher was born in Mulberry, Indiana.

Slipher was director of the Lowell Observatory in Arizona, and the first to discover the redshift of galaxies when he obtained their spectra and measured their radial velocities. This laid the foundation for the work that Edwin Hubble's work on the expansion of the Universe.
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On this day in 1910 – November 11th – American astronomer Carl Alvar Wirtanen was born in Kenosha, Wisconsin.

Wirkenen worked at Lick Observatory in California. He's best known for his discovery of periodic comet 46P/Wirtanen and eight asteroids. On the comet's 2018 visit, it was dubbed the Christmas Comet. It was bright green, and visible in dark skies as a naked eye object. [The beautiful photo of the comet is by Tommy Eliassen.]
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On this day in 1891 – November 12th – American astronomer Seth Barnes Nicholson was born in Springfield, Illinois.

Nicholson worked at Mount Wilson Observatory in California for over 40 yrs, mainly concerned with solar activity. But he also computed the orbit of several comets, discovered a Trojan asteroid, and is probably best remembered for his discovery of four satellites of Jupiter.
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On this day in 2014 – November 12th – the Philae probe became the first spacecraft to land on a comet.

Philae was the lander part of the Rosetta mission of the European Space Agency (ESA) to comet 67P/Churyumov-Gerasimenko.
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On this day in 1680 – November 14th – German astronomer Gottfried Kirch discovered the comet C/1680 V1.

It was the first comet to be discovered using a telescope, and became one of the brightest comets of the 17th century.
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On this day in 1971 – November 14th – NASA's Mariner 9 was inserted into Martian orbit.

Mariner 9 was the first spacecraft to orbit Mars.
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On this day in 1738 – November 15th – William Herschel was born in Hannover, now part of Germany. He later moved to England and acquired British citizenship.

Herschel, with the assistance of his sister Caroline, helped to lay the foundations of modern astronomy. He was also an international celebrity as the first person in history to discover a new planet. We know it as Uranus, but Herschel called it Georgium Sidus (George's Star) in honor of King George III.
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On this day in 1995 – November 17th – the European Space Agency (ESO) launched the Infrared Space Observatory (ISO).

As the first orbiting infrared observatory, it finally made it possible for astronomers to make sensitive observations at infrared wavelengths.
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On this day in 1923 – November 18th – NASA astronaut Alan Shepard was born in East Derry, Derry, New Hampshire.

NASA astronaut Alan Shepard was born in East Derry, Derry, New Hampshire.
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On this day in 1989 – November 18th – NASA's Cosmic Background Explorer (COBE) was launched.

COBE was a cosmology satellite that investigated the cosmic microwave background radiation (CMB). It provided key pieces of evidence that supported the Big Bang theory of the Universe.
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On this day in 2013 – November 18th – NASA's MAVEN spacecraft was launched.

The Mars Atmosphere and Volatile Evolution Mission (MAVEN) is a space probe designed to study the Martian atmosphere from Mars orbit.
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On this day in 1969 – November 19th – Apollo 12 astronauts landed on the Moon in the southeastern part of the Ocean of Storms.

Mission commander Charles "Pete" Conrad and Lunar Module Pilot Alan L. Bean carried out lunar surface tasks. Command Module Pilot Richard F. Gordon remained in lunar orbit.
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On this day in 2005 – November 19th – the Hayabusa spacecraft of the Japan Aerospace Exploration Agency (JAXA) became the first ever to lift off from an asteroid.

It had collected a sample of material from near-Earth asteroid 25143 Itokawa, which it then returned to Earth.
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On this day in 1889 – November 20th – American astronomer Edwin Hubble was born in Marshfield, Missouri.

He showed that the Universe was much bigger than our own Galaxy, and his observations and those of Vesto Slipher provided evidence for an expanding universe. The Hubble Space Telescope is named for him.
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On this day in 2004 – November 20th – NASA's Swift Gamma-Ray Burst Mission was launched. (It's now called the Neil Gehrels Swift Observatory.)

The mission, with international participation, was designed to help solve the mystery of gamma-ray bursts.
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On this day in 1977 – November 23rd – Meteosat-1 was launched by EUMETSAT (a European intergovernmental agency).

Meteosat-1 was the first of the first generation of Meteosat satellites, which have provided continuous and reliable meteorological observations from space to a large user community.
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On this day in 1816 – November 25th – American lawyer, astronomer and pioneering astrophotographer Lewis Morris Rutherfurd was born in Morrisania, New York.

After practicing law for a number of years, Rutherfurd gave it up for astronomy. He was a pioneer of astrophotography, inventing the first telescope designed specifically for astrophotography. With the telescope he made high quality images of the Sun, Moon and planets as well as star clusters and stars down to around fifth magnitude. Rutherfurd was an associate of the Royal Astronomical Society, and one of the original members of the National Academy of Sciences.
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On this day in 2011 – November 26th – the Mars Science Laboratory rover Curiosity was launched.

Curiosity is still exploring Mars.
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On this day in 1701 – November 27th – Swedish astronomer, mathematician and physicist Anders Celsius was born in Uppsala.

Best known for his 'degrees Celsius' temperature scale, he was also professor of astronomy at Uppsala University. He also created the Celsius Observatory in Uppsala.
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On this day in 1885 – November 27th – the first known photograph of a meteor was taken.

Austro-Hungarian astronomer Ladislaus Weinek caught a 7mm-long trail at his Prague observing station during the Andromedid meteor shower. (Since the 19th century the Andromedids have faded so much that they're no longer generally visible to the naked eye.)
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On this day in 1971 – November 27th – the Soviet Mars 2 probe became the first man-made object to reach the surface of Mars.

However, it wasn't the first successful mission, because the landing system failed and the lander was lost.
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On this day in 1964 – November 28th – NASA's Mariner 4 was launched.

The spacecraft made the first successful flyby of the planet Mars, returning the first pictures of the Martian surface. They were the first images of another planet ever returned from deep space.
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On this day in 1967 – November 28th – at the Mullard Radio Astronomy Observatory in Cambridge, England, the first pulsar was observed by Jocelyn Bell and Antony Hewish.

A pulsar is a rapidly rotating neutron star, but at the time no one knew this. A neutron star was still a theoretical construct whose existence wasn't generally accepted by astronomers.
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On this day in 1967 – November 29th – Australia became the 4th nation to launch a satellite from its own territory.

The satellite (Wresat) was a joint venture of the Weapons Research Establishment and the University of Adelaide's Physics Department. It collected and sent back data about the composition of the upper atmosphere for 73 orbits.
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On this day in 1609 – November 30th – Galileo Galilei made his first detailed observations of the Moon using a telescope.

Using a telescope with 20x magnification, he observed and drew the Moon from 30 November to 18 December.
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On this day in 2013 – December 1st – China's Chang'e-3 spacecraft was launched to the Moon.

It was made up of a lander plus the rover Yutu which would be deployed for a time on the lunar surface.
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On this day in 1993 – December 2nd – the first Hubble Space Telescope servicing mission was launched.

The crew of the Space Shuttle Endeavour went to the telescope with a new main camera and a corrective optic package to restore the telescope's blurred vision.
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On this day in 1995 – December 2nd – the NASA/ESA Solar and Heliospheric Observatory (SOHO) was launched.

It was originally planned as a two-year mission, but it's still providing essential data about the Sun and space weather.
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On this day in 2015 – December 3rd – ESA's LISA Pathfinder was launched.

LISA (Laser Interferometer Space Antenna) conducted in-flight testing for the concept of low-frequency gravitational wave detection..

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On this day in 1639 – December 4th – Jeremiah Horrocks and William Crabtree were the first people ever to observe a transit of Venus. They were observing in the north of England.

Horrocks had predicted the transit based on his own corrections to Kepler's Rudolphine Tables..

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On this day in 1997 – December 4th – NASA's Mars Pathfinder was launched.

Mars Pathfinder was a robotic spacecraft that landed a base station (named the Carl Sagan Memorial Station) and Sojourner, the first roving probe on Mars..

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On this day in 1968 – December 6th – ESRO (a precursor to the European Space Agency) had its Highly Eccentric Orbit Satellite (HEOS-1) launched from Cape Kennedy.

It was the first European satellite to venture beyond near-Earth space. It studied magnetic fields, radiation and the solar wind, which required an orbit stretching two-thirds of the way to the Moon..

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On this day in 1998 – December 6th – the Unity and Zarya modules were connected to form the core of the International Space Station (ISS).

The ISS was first occupied on November 2, 2000 and has been in continuous occupation ever since.

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On this day in 1676 – December 7th – the first news was published of Danish astronomer Ole Rømer's measurement of the speed of light.

Rømer's work was based on observations of the eclipses of the moons of Jupiter. At that time not everyone was convinced that light even had a finite speed.

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On this day in 1905 – December 7th – Gerard Kuiper was born in Tuitjenhorn, Netherlands.

Among the Dutch-American astronomer's discoveries is Neptune's moon Miranda. The Kuiper Belt is named for him, and he is considered by many to be the father of modern planetary science.

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On this day in 1995 – December 7th – NASA's Galileo spacecraft entered Jupiter's atmosphere and began its prime mission.

Galileo was the first spacecraft to orbit Jupiter, though others had made fly-bys of the giant planet.

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On this day in 2018 – December 7th – China launched the Chang'e 4 lunar spacecraft mission.

The mission included a robotic lander and the rover Yutu-2.

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On this day in 1842 – December 8th – French astronomer Alphonse Louis Nicolas Borrelly was born in Roquemaure (Gard) in southern France.

At the Marseille Observatory, Borrelly discovered 18 asteroids and discovered or co-discovered at least six comets, including the periodic comet 19P/Borrelly. That comet was photographed by NASA's Deep Space 1 in September 2001. The comet last came to perihelion (closest approach to the Sun) on February 1, 2022.

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On this day in 1999 – December 10th – the European Space Agency (ESA) launched the Newton X-Ray Multi-Mirror Telescope (XMM-Newton).

XMM-Newton, named for Sir Isaac Newton, investigates interstellar X-ray sources. It performed the first simultaneous imaging of objects in both X-ray and optical (visible and ultraviolet) wavelengths. Although planned to be operational for 10 years, the telescope is still in operation..

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On this day in 1863 – December 11th – American astronomer Annie Jump Cannon was born in Dover, Delaware.

Cannon classified nearly a quarter of a million star spectra for the Henry Draper Catalogue and oversaw its publication after the death of Edward Pickering, the Harvard College Observatory director..

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On this day in 1805 – December 13th – Scottish-German astronomer Johann von Lamont (John Lamont) was born in Corriemulzie in Aberdeenshire, Scotland.

He calculated the orbits of moons of Uranus and Saturn, but his most important work was on the Earth's magnetism..

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On this day in 1904 – December 13th – theoretical physicist Sir William Hunter McCrea was born in Dublin, Ireland.

McCrea made contributions to mathematics, physics and almost every area of astronomy, but is best known for his seminal work in modern relativistic cosmology. He was elected a Fellow of the Royal Society and the Royal Society of Edinburgh, the Royal Astronomical Society, the Royal Irish Academy, and was awarded many other honors..

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On this day in 1546 – December 14th – Danish astronomer Tycho Brahe was born in Knudstrup, Scania, then part of Denmark.

Tycho was the greatest ever observer in the days before the telescope. His extensive collection of accurate observations made it possible for Kepler to work out the orbits of the planets..

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On this day in 1962 – December 14th – NASA's Mariner 2 made the first successful planetary flyby when it had its encounter with Venus.

The last transmission from the spacecraft was received on January 3, 1963, but it remains in heliocentric orbit..

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On this day in 2013 – December 14th – the China National Space Administration (CNSA) Chang'e-3 spacecraft landed on the Moon.

The craft was composed of a lander and the Yutu rover. It was the first soft landing on the Moon since the Soviet Union's Luna 24 in 1976..

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On this day in 1826 – December 16th – Italian astronomer Giovanni Battisti Donati was born in Pisa.

He's best remembered for the discovery of several comets, including the one that is named for him. Donati's comet was a spectacular sight in the sky in late 1858..

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On this day in 1857 – December 16th – American astronomer Edward Emerson Barnard was born in Nashville, Tennessee.

He was one of best visual observers of his day, as well as a pioneer of celestial photography. Barnard's Star was named for him. It's a red dwarf star for which Barnard measured its proper motion relative to the Sun..

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On this day in 1917 – December 16th – British author, futurist, inventor and explorer Arthur C. Clarke was born in Minehead, Somerset, England.

Clarke wrote more than 100 books, and he inspired scientists and space explorers. In honor of his work, the International Astronomical Union named the distance of 36000 km above Earth the Clarke Orbit, and in 2018 they named a mountain on Pluto's moon Charon for him..

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On this day in 1999 – December 18th – NASA launched the Terra satellite.

Terra was the flagship of the Earth Observation System, a multinational research program to study changes in the Earth and how they could affect life on our planet. It's still operational..

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On this day in 1904 – December 20th – The Mount Wilson Solar Observatory in Los Angeles County, California was founded.

About fifteen years later, "solar" was dropped from the name as the 100-inch Hooker telescope came into use. Observing with it, Edwin Hubble found evidence that the Milky Way was just one galaxy in an expanding Universe..

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On this day in 1986 – December 21st – NASA launched Apollo 8 with a crew of Frank Borman, Jim Lovell and William Anders.

The Apollo 8 Moon mission was the first manned mission to leave Earth orbit and go into orbit around another celestial object.

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On this day in 1998 – December 21st – Vladimir Titov and Musa Manarov returned to Earth.

The two cosmonauts had spent an entire year aboard the Soviet Mir space station..

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On this day in 2023 – December 22nd – the winter solstice occurred at 03:27 UCT (Coordinated Universal Time), i.e., Greenwich Mean Time. In North America, the solstice was on December 21st in various time zones.

The winter solstice is is the shortest day of the year in the northern hemisphere, and the North Pole is at its maximum tilt away from the Sun. The southern hemisphere has its longest day and, the South Pole is at its maximum tilt towards the Sun..

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On this day in 2022 – December 24th – Apollo 8 entered lunar orbit.

The crew - Frank Borman, James Lovell & Wiliam Anders - were the first humans to view Earth as a whole planet, the first to orbit another world, and the first to see the far side of the Moon. They made a live Christmas Eve broadcast to the Earth as they circled the Moon..

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On this day in 1758 – December 25th – German amateur astronomer Johann Georg Palitzsch became the first to view Halley's Comet on its return to the inner solar system.

The comet's return had been predicted by the English scientist and astronomer Edmond Halley, after whom it was subsequently named..

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On this day in 2003 – December 25th – the European Mars Express and British Beagle 2 arrived at Mars.

Beagle 2 was damaged on landing and never responded, but the orbiter Mars Express is still returning data.

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On this day in 2004 – December 25th – the Huygens probe separated from the Cassini spacecraft.

Huygens went on to land on Saturn's moon Titan, and Cassini studied the Saturnian system until 2017..

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On this day in 2021 – December 25th – the James Webb Space Telescope was launched on an Ariane 5 rocket from Kourou, French Guiana.

As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble Space Telescope. This enables investigations across many fields of astronomy and cosmology, such as observation of the first stars, the formation of the first galaxies, and detailed atmospheric characterization of potentially habitable exoplanets..

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On this day in 1780 – December 26th – Mary Somerville was born in Jedburgh, Scotland.

Somerville was one of the leading lights of 19th century science. She was an able mathematician and she published books on developments in astronomy, physics and geography. Somerville was honored by several learned societies, even though, as a woman, she would not have been allowed to attend their meetings..

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On this day in 1571 – December 27th – Johannes Kepler was born near Stuttgart in Germany.

Using the data of Tycho Brahe, Kepler formulated the three laws planetary motion which were the foundation for our modern view of the Solar System. They could describe planetary orbits simply, but required the Sun - not the Earth - to be at the center of the Solar System..

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On this day in 1789 – December 28th – Scottish astronomer Thomas Henderson was born in Dundee, Scotland.

He was based at the Royal Observatory, Cape of Good Hope, South Africa during the early 1830s. After his return to his native Scotland, he became Astronomer Royal for Scotland in 1834, a post he held until his death in 1844..

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On this day in 1882 – December 28th – English astrophysicist Arthur Eddington was born in Kendal, Westmorland, England.

Eddington was one of the most eminent scientists of his day, and was made famous by testing Einstein's theory of general relativity during a total solar eclipse..

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On this day in 2005 – December 28th – GIOVE-A, the first Galileo satnav system satellite, was launched.

Galileo is Europe's global navigation satellite system, developed under a partnership between the European Space Agency (ESA) and the European Commission (EC)..

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On this day in 1888 – December 29th – pioneering Welsh astrophotographer Isaac Roberts took the first detailed picture of another galaxy, the Great Nebula in Andromeda.

Roberts went on to systematically photograph the brightest nebulae and star clusters visible from England, and received international recognition for his work..

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On this day in 1928 – December 30th – Belgian astronomer Henri Debehogne was born in Maillen, Belgium.

Debehogne worked at the Royal Observatory of Belgium in Uccle where he specialized in the astrometry of comets and minor planets. The Minor Planet Center of the International Astronomical Union (IAU) credited him with over 700 discoveries of minor planets...

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On this day in 1744 – December 31st – English astronomer James Bradley announced the discovery of Earth's nutation motion. Bradley was a distinguished academic at Oxford and later became the third Astronomer Royal at Greenwich.

Nutation is a phenomenon which causes the orientation of the axis of rotation of a spinning astronomical body to vary over time. Earth's nutation is caused by the gravitational forces of the Sun and Moon..