An alien planet orbits a star other than our sun, and is sometimes called an "exoplanet." Learn more about the types of alien planets, including exoplanets and extrasolar planets, and get the latest news.
It's unclear what, exactly, Kepler has found; a media advisory about the news briefing didn't give any specific clues. You can find out by listening to the 1 p.m. EDT (1700 GMT) Tuesday briefing live here at Space.com, courtesy of NASA.
Gliese 581g is an extra-solar planet that was discovered in 2010, but quickly cast into doubt by other studies. The original discoverers then published a follow-up paper in 2012 defending their find.
Stephen Hawking, Yuri Milner and Mark Zuckerberg helm the board for a new initiative, Breakthrough Starshot, whose technology could be used to someday reach Earth's neighboring star Alpha Centauri after just a 20-year journey.