![]() ![]() They're enveloped by hot, tenuous atmospheres and are likely uninhabitable, researchers say. Two of those planets orbit cool, red dwarf stars and are what astronomers call mini-Neptunes: K2-416 b, which is 2.6 times wider than Earth and orbits its star once every 13 Earth days and K2-417 b, which is three times wider than Earth and circles its star every 6.5 days.īoth worlds are smaller than Neptune. In that limited dataset, which included information about 33,000 additional stars, the team spotted one transit each for three exoplanets around three dim stars. Kepler fought on for four more years and gazed at different slices of the sky once every 80 days, on a new mission known as K2 during which it discovered hundreds more exoplanets.īy late August 2018, Kepler's observation power had deteriorated so much that the month-long K2 Campaign 19 - Kepler's final observation cycle - yielded only a week of high-quality data, the team wrote in the new study. But two of its four reaction wheels - devices crucial to point the observatory at its targets - failed in 2013, and it was no longer able to focus on stars precisely.Ī year later, scientists implemented a work-around solution that used the telescope's two good reaction wheels and its onboard thrusters to maintain a slightly unstable but workable balance. Kepler's first four years in space went smoothly. The spacecraft documented dips in starlight that hinted at orbiting planets - a technique known as the "transit method." ![]() The Kepler telescope launched in March 2009 to stare at 150,000 selected stars in the constellation Cygnus, on a primary mission expected to last 3.5 years. ![]()
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