The year 2018 was a good one for astronomers. Mars, asteroids, and the outer Solar System had the spotlight more than once. Gaia is bringing the Milky Way into focus, and Hubble found the most distant star ever seen. Here are my choices for the top astronomy stories of 2018.

Top Ten Astronomy Stories of 2018

A sample animation from the Gaia data release

The orbits of four globular clusters (NGC 104, NGC 288, NGC 362 and NGC 1851), shown in blue, and three dwarf galaxies (Carina, Bootes I and Draco), shown in red, around the Milky Way, as imaged by the Gaia spacecraft.
Credit: ESA/Gaia/DPAC

The missions of Voyager 2

Voyager 2's primary mission was to visit Jupiter, Saturn, and Uranus in 1979, 1981 and 1986. It's been operational for over four decades. After visiting the giant planets, the spacecraft then traveled through the Kuiper Belt, and is now on a mission of interstellar space. NASA maintains contact through its Deep Space Network.

When Voyager stopped transmitting signals showing the particles of the solar wind, scientists knew that it had crossed the boundary of the heliosphere. Within the heliosphere the Sun is dominant. Outside it, there are influences from outside the Solar System - it's a region of the space between the stars.

Object 2018 VG18 - nicknamed Farout - is the first first solar system object detected at a distance of more than 100 times Earth's distance from the sun.

Scott S. Sheppard of the Carnegie Institution of Science, David Tholen of the University of Hawaii and Chad Trujillo of Northern Arizona University were the discoverers. They said:

NASA's still-silent Opportunity rover was spotted at the end of September in images taken by the Mars Reconnaissance Orbiter (MRO) at about 267 km above the Martian surface. The dust storm over Perseverance Valley had substantially cleared by then.

NASA will continue to look out for signals from Opportunity until the end of this month, but has already stopped attempting to contact the rover.

The little rover has been a wonder and a tremendous asset, having explored Mars for fourteen years. When Opportunity and its sister Spirit arrived on the red planet, it was assumed they would last not much more the 3 months before the Martian dust covered their solar panels and shut down their power.

TESS, the Transiting Exoplanet Survey Satellite, (left) will search nearly the entire sky for alien worlds. TESS should find many worlds (center) for other telescopes to target by surveying 2.5 million stars, four sky sectors at a time (right).

[Left and Right: Chester Beals/MIT; Center: NASA/JP]

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