The Most Incredible Alien Planet Discoveries of 2016

1) Proxima Centauri b

A planet in its star's "habitable zone" — a region where it's not too hot or too cold for liquid water to exist on a planetary surface — was found practically in our planet's backyard this year. Called Proxima Centauri b, the planet was found during a unique campaign called Red Blue Dot where astronomers shared details of their search on social media in the first few months of 2016. The planet is believed to be about 1.3 times the mass of the Earth and orbiting about 5 percent of the Earth-sun distance from its cool parent star. The team was led by Guillem Anglada-Escudé, from Queen Mary University of London.

2) TRAPPIST-1

Artist's impression of the dwarf star TRAPPIST-1 and its three planets, which are similar in size and temperature to Venus and Earth.

TRAPPIST-1's three planets were quite the astronomical find. The research team uncovered evidence of three Venus- and Earth-sized exoplanets, which was extraordinary given that TRAPPIST-1 is an ultracool dwarf star and no planets have ever been found around a star of this type. Finds like this are exciting because it's easier to observe planetary atmospheres — especially for habitable environments — if the star is fairly dim. The team was led by Michael Gillon, of the the Institute of Astrophysics and Geophysics at the Unviersity of Liege in Belgium.

3) Planet rings spinning the wrong way

Artist's impression of the bizarre ring system of J1407b.

In 2015, researchers proposed that a bizarre series of eclipses around the star J1407 could be caused by a planet with a huge ring system. Then earlier this year, the team published another paper suggesting that the system would only work if the rings orbited around the planet in the opposite direction that the planet orbits its parent star! As unstable as this sounds, their calculations suggest the planet's rings could persist for more than 100,000 years. The research was led by Matthew Kenworthy of Leiden University, in the Netherlands.

4) Three planets around two close stars

Artist's impression of three planets orbiting two close binary stars.

We've all heard of several Tattooine-like systems similar to "Star Wars", where a planet orbits two stars. But we're starting to discover some even more bizarre combinations. Scientists found a system in which three planets orbit two stars that are very close together (the closest ever observed). The stars are called HD 133131A and HD 133131B. Researchers are now studying this system closely to see if Jupiter-like planets often begin with long and eccentric orbits. The team was led by Johanna Teske of the Carnegie Institution for Science.

5) One planet orbiting three stars

Artist's impression of a planet in the HD 131399 system, orbiting three stars.

It seems strange to think of a single planet somehow surviving a three-star orbit, but such a world has been discovered. The HD 131399 system features a planet with the widest known orbit in a multi-star system. While astronomers thought this type of orbit was unlikely, since they have found one they expect to find many others. The team was led by Kevin Wagner at the University of Arizona.

6) Kepler's new mission yields 100-plus exoplanets

Artist's impression of the Kepler space telescope on its K2 mission.

A few years ago, the Kepler space telescope — a venerable exoplanet hunter — lost the ability to point precisely with its reaction wheels. NASA devised a new mission using the sun's pressure to steady the telescope, and it's been far more productive than expected. This year, the so-called K2 mission announced that it has yielded 104 exoplanets. One of the most promising finds among these was the star K2-72, which has four planets that could be rocky.

7) Kepler's database yields more than 1,200 exoplanets

Artist's impression of some of the Kepler's many planetary discoveries.

Although the Kepler telescope's primary mission is over, the data from its years of observations persist. NASA is doing ongoing analyses to see how many of these planetary candidates are likely to be planets. The latest results show that 1,284 of them are 99 percent likely to be planets. Of these, nearly 550 are likely rocky planets — and nine of those potentially rocky planets are in the habitable zone of their stars.

8) Baby planet just 11 million years old

Artist's impression of a young planet orbiting the star K2-33.

Earlier this year, astronomers announced they had found the youngest known planet — just 11 million years old, a fraction of the Earth's 4.5 billion years. It's a super-Neptune roughly five times the size of Earth and orbits its star only five million miles away, making it a scorching world. It was first found with the K2 mission and then confirmed with the MEarth-North and MEarth-South arrays in Arizona and Chile, just to make sure it wasn't a starspot. The research was led by Andrew Mann at The University of Texas at Austin.

Read more at Discovery News