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Posted By: Mona - Astronomy Astronomy / Space Advent - 11/30/17 06:06 AM
Watch this space! There won't be any windows to open or hidden chocolates, but starting tomorrow there will be a link to follow for each day to a picture relating to a significant event or stunning astro image. Finishing with one on Christmas Day.

I like advent calendars, so I've chosen this as my holiday theme. But I'm reaching out to everyone who is celebrating a winter holiday. Yes, and the Bah! Humbug! folk too.
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/01/17 06:03 AM
1

On December 1, 2013 China launched Chang'e-3 to the Moon carrying the rover Yutu.

The spacecraft landed two weeks later and the rover was deployed.

Chang'e was a Chinese goddess who flew to the Moon, and Yutu was her rabbit companion. In 1969 during the Apollo 11 moon landing, Houston told the astronauts of this Chinese legend. Buzz Aldrin said, “Okay. We’ll keep a close eye out for the bunny girl.”
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/02/17 04:54 AM
2

On December 2, 1995 the NASA/ESA Solar and Heliospheric Observatory (SOHO) was launched.

A montage of SOHO images shows its view of the Sun at different ultraviolet wavelengths.

The images correspond to solar material at a range of temperatures. From left to right, the brightest material in each image corresponds to temperatures of 60 000–80 000ºC, 1 million, 1.5 million and 2 million degrees respectively. The higher the temperature, the higher you are looking in the solar atmosphere. The hottest areas appear brighter, while the darker regions are relatively cooler.
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/03/17 04:59 AM
3

On December 3rd the full Cold Moon will appear as what's commonly called a “supermoon”.

Here is such a moon over Paris in 2012. (photo: VegaStar Carpentier)

The Moon's orbit isn't a perfect circle, so there's a time when the Moon is at its closest (perigee) and another when it's at its most distant (apogee). A supermoon is a full moon at perigee. It appears somewhat larger and brighter than the average full moon. However, for all the fuss, you'd be very unlikely to notice the difference. You're more likely to see the Moon low in the sky look larger than usual – this is a well known illusion. The moon in the photograph rising behind the Eiffel Tower doesn't look enormous because it's a supermoon. Photographers create this illusion by increasing their distance to the foreground object.

You can find out more in What Is a Supermoon?
Posted By: Angie Re: Astronomy / Space Advent - 12/03/17 01:51 PM
It looked like a full moon last night but not very large from where I was sitting. Does one day make a difference or is it in just a few places?
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/03/17 05:54 PM
The time of a full moon is predictable and precise. However just looking at up, the Moon can look full for a day either side. A so-called supermoon doesn't actually look any larger than the usual full moons. If you put photographs of a "supermoon" (perigee Moon, i.e., closest to Earth) and a "minimoon" (apogee Moon, i.e., farthest from Earth) side by side, you can see a difference. If you just look up in the sky, you can only see what's there at that time.
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/04/17 04:23 AM
4

On December 4, 1639, Jeremiah Horrocks and William Crabtree were the first people ever to observe a transit of Venus.

Here is a dramatic photo of the Sun with transiting Venus rising over the Black Sea in the transit of June 6, 2012. (Image credit & copyright: Emil Ivanov)

You can find out more about the first transit in Transit of Venus .
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/05/17 03:25 AM
5

One of the most magnificent sights of winter in the far north (or south) is an aurora.

Here is a prize-winning photo of the northern lights above the village of Reine in the Lofoten Islands, Norway. (Image credit & copyright: Alex Conu) It was the winner of The World at Night's 2016 International Earth and Sky Photo Contest.

You can find out more about aurorae here.
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/06/17 06:20 AM
6

On December 6, 1998 the Unity and Zarya modules were connected to form the core of the International Space Station (ISS).

From that has grown the amazing amazing ISS we have today.

If you want to find out more about life on the space station, here is a video in which NASA astronaut Sunita Williams gives a guided tour.
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/07/17 06:16 AM
7

On December 7, 1676 a report of Danish astronomer Ole Rømer's presentation to the Royal Academy of Sciences in Paris on the speed of light was published. (ISS).

Here is an animated cartoon celebrating Rømer's work. At the time, the speed of light was assumed to be infinite, but Rømer used his timings of the eclipses of Jupiter's moon Io to show otherwise.
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/08/17 03:07 AM
8

An annular eclipse and a total solar eclipse graced 2017, as well as a penumbral lunar eclipse (scarcely noticeable to the untrained eye) and a partial lunar eclipse.

Here are the four eclipses of 2017. (Image Credit & copyright: Petr Horálek)
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/09/17 05:57 AM
9

Venus is closer to the Sun than we are, so it has phases like the Moon does. Nobody knew this until the invention of the telescope, because you can't see the apparent shape changes with just the unaided eye.

Here is a beautiful sunset view of Venus in crescent phase taken with a long telephoto lens. (Image Credit & copyright: Jay Ouellet) In 1610 Galileo was the first person to observe the phases of Venus. They couldn't happen if the prevailing Earth-centered view of the Solar System was correct, but supported the Copernican Sun-centered view.
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/10/17 11:25 AM
10

The Juno mission has been orbiting Jupiter since the summer of 2016, getting closer to the giant planet than any spacecraft before it – it's designed to get as close as 4100 km (2600 miles).

Here is a view of Jupiter's complex turbulent clouds when the high altitude clouds were casting a shadow on their surroundings. Doesn't it look like an abstract painting?
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/11/17 05:42 AM
11

On December 11, 1863 American astronomer and suffragette Annie Jump Cannon was born.

Cannon devised what became the Harvard Classification System for stars, and she herself classified the spectra of around a quarter of a million stars for the Henry Draper Catalog. This picture shows the spectral lines of a number of common elements superimposed on a visible light spectrum. Cannon once said, “Each new spectrum is the gateway to a wonderful new world. It is almost as if the distant stars had really acquired speech and were able to tell of their constitution and physical condition.”

Annie Cannon also devised the Harvard stellar classification. The order of the star classes from hottest to coolest went: OBAFGKM.To remember the order, here's the traditional mnemonic: Oh, Be A Fine Girl [Guy] – Kiss Me. It's probably not allowed anymore.
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/12/17 05:35 AM
12

Dwarf planet Pluto, gateway to the Kuiper Belt, is one of the Solar System's most amazing objects.

This New Horizons image shows Pluto's “heart”, the region named Tombaugh Regio. The different colors represent different compositions of surface ices. They reveal that Pluto is an active body even though it's small and very cold. (Image: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/13/17 04:38 AM
13

The Geminid meteor shower is a December spectacle. It's produced by debris left behind by asteroid 3200 Phaethon, and runs annually from December 7-17. It peaks this year on the night of the 13th and morning of the 14th.

This composite photo shows Geminid meteors seen from the summit of Mt Changbai along China's northeastern boarder with North Korea. (Image: Jia Hao) The shower's radiant in the constellation Gemini is to the upper left, at the apparent origin of all the meteor streaks. Orion is near picture center above the volcanic cater lake. 
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/14/17 04:10 AM
14

Danish astronomer Tycho Brahe was born on December 14, 1548. His astronomical observations were key to formulating the modern view of the Solar System.

Here is Lunar Reconnaissance Orbiter's sunrise view of the central peak of Tycho Crater on the Moon. (Image Credit: NASA/Goddard/Arizona State University) The complex is some 15 km (9.3 mi) wide within a crater over 80 km (50 mi) in diameter. The central peak's summit is 2 km (1.2 mi) above the crater floor.
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/15/17 05:22 AM
15

On December 15, 1970 the Soviet probe Venera 7 landed on Venus. It was the first spacecraft to do so. It survived for 53 minutes, 20 of them on the surface.

Venera 7 sent back some data, but the study of Venus has become much more sophisticated since then. This is a computer generated 3D perspective view of three craters on Venus. The image was created using data from NASA's Magellan spacecraft, with coloring based on Venera 13 and 14 Lander images.
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/16/17 05:33 AM
16

On December 16, 1917, Arthur C. Clarke was born. He was an influential science writer and science fiction writer.

Clarke envisioned many of the features of our present technology, such as satellite communications, that seemed to be fantasy at the time. His work inspired a number of scientists, but best known to the public is the book that was made into a film by Stanley Kubrick. Here is an infographic about 2001: A Space Odyssey. [A click enlarges it.]
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/17/17 06:27 AM
17

This is a cosmic pillar of dust in the Carina Nebula. It's two light years long and inside it is a young star emitting powerful jets. The pillar's layered outline is shaped by the winds and radiation of Carina's massive hot young stars. The Carina Nebula, about 7500 light years away, is visible in the southern hemisphere.

Here is a view in infrared light showing two narrow jets blasting outward from a still hidden infant star.

(Image Credit: NASA, ESA, Hubble, HLA; Processing & Copyright: Domingo Pestana; Description adapted from Robert Nemiroff (MTU) & Jerry Bonnell (UMCP))
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/18/17 03:21 AM
18

How is the Earth changing and what are the consequences for life on Earth? This and related questions prompted the creation of the Earth Observing System (EOS), a multinational research program. On December 18, 1999 NASA launched the Terra satellite, the flagship of EOS.

Terra has several instruments, one of them ASTER which collects data that can create detailed maps of land surface temperature. This image was acquired on October 21, 2017 over the area of northern California that was burning in some of the most destructive fires in California history. [Click to enlarge the picture.] In the image, vegetation is red, while burned areas appear dark gray. The image covers an area of 38 by 39 miles (60.5 by 63 km).

(Image Credit: NASA/METI/AIST/Japan Space Systems,and U.S./Japan ASTER Science Team)
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/19/17 05:58 AM
19

Do other stars have planetary systems similar to ours? Yes – one such system is  Kepler-90. It has the same number of known planets as our Solar System.

Kepler-90's G-type star is comparable to our Sun, there are rocky planets comparable to Earth, and large planets comparable in size to Jupiter and Saturn. However a major difference is that all of the known Kepler-90 planets orbit relatively close in – closer than Earth's orbit around the Sun – making them likely to be too hot to harbor life. Kepler-90 lies about 2,500 light years away, in the constellation Draco (the Dragon).

(Image Credit: NASA Ames, Wendy Stenzel)
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/20/17 05:32 AM
20

On December 20, 1904 George Ellery Hale founded the Mount Wilson Solar Observatory.

Later the “solar” was dropped when the observatory's 100-inch telescope – the biggest in the world – went into action. Edwin Hubble used the telescope and discovered that our galaxy wasn't alone, and found evidence for an expanding Universe.

In September 2009 the historic research facility was threatened by wildfire when southern California fires were blazing out of control. The picture shows a view of the encroaching fire from the observatory. Fortunately, concerted action by firefighters kept the blaze from engulfing it. There was heat and smoke damage, but it survived intact.

(Image Credit: UCLA Department of Physics and Astronomy)
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/21/17 06:23 AM
21

December 21 is the day of the winter solstice in the northern hemisphere. It's the shortest day, and the Sun reaches its most southerly point on the celestial sphere at 16:28 UTC (11:28 a.m. EST).

If you took a picture of the Sun from the same place and at the same time each day, you wouldn't see the Sun in the same position. The shape traced out by the Sun over a year is called an analemma. Today, in the northern hemisphere, the Sun is at the bottom of the analemma. The analemma in this photo was built up by 46 separate Sun photographs taken during 2003 in Athens, Greece. Pictured in the foreground of the composite image are pillars called the Porch of Maidens, part of the ancient Erechtheum which was completed in 407 BC.

(Image Credit: UCLA Department of Physics and Astronomy
Description based on text by: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP))
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/22/17 05:29 AM
22

One of the most daring space missions of the new millennium was the Rosetta mission to a comet.

Launched in 2004 into the outer Solar System, Rosetta lay in wait for the right time to pursue Comet 67P/Churyumov-Gerasimenko. The spacecraft caught up with the comet as it headed into towards the Sun, and went into orbit around it.

One big question about comets has been: Where do comet tails come from? The question isn't yet conclusively answered, but there's more to work on now. In this photo we see a jet emerging from the comet, a bright plume coming out of a small circular dip bounded on one side by a 10-meter high wall. Rosetta flew right through the plume and analysis showed it was dust and water-ice.

(Image Credit: ESA, Rosetta, MPS, OSIRIS; UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA 
Description adapted from Robert Nemiroff (MTU) & Jerry Bonnell (UMCP))
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/23/17 07:31 AM
23

On December 23, 1672 Jean-Domenique Cassini discovered Saturn's moon Rhea.

Almost exactly 338 years later, the Cassini spacecraft took a picture of Rhea. This is a false color image of Rhea that emphasizes the differences between the hemisphere that leads as Rhea orbits, and the trailing hemisphere. It's not unusual for large icy Saturnian satellites to exhibit hemispheric albedo (reflectivity) and color differences.

(Image Credit: NASA/JPL/SSI)
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/24/17 06:11 AM
24

On December 24, 1968, Apollo 8 entered lunar orbit. Three NASA astronauts – Frank Borman, Jim Lovell, and William Anders – became the first humans to orbit a body other than Earth, and to see the far side of the Moon.

Their photo ”Earthrise” remains a moving reminder of the fragility of our beautiful planet.

But it was Christmas Eve, and no human had ever been so far from home before. The crew held a live broadcast from lunar orbit, showing pictures of the Earth and Moon taken from their spacecraft. They ended the broadcast with the crew taking turns reading from the book of Genesis.

(Image Credit: NASA)
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/25/17 07:18 AM
*25*

Sir Isaac Newton, one of the greatest physicists of all time, was born in Lincolnshire in England on Christmas Day 1642, on the Julian calendar then in use.

Newton was inspired to link objects falling to Earth, such as an apple from his apple tree, to movements in the heavens. He united them in his theory of gravitation. Here is a picture of Newton's home Woolsthorpe Manor and a descendant of the apple tree.

Image credit: DS Pugh
Posted By: Mona - Astronomy Re: Astronomy / Space Advent - 12/25/17 07:31 AM
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