NASA/JPL-Caltech
A research team worked with a group of citizen scientists and professional astronomers and found three planets in the last bit of data.
A team of astrophysicists and citizen scientists have identified some of the last planets NASA's retired Kepler space telescope observed during its nearly decade-long mission, NASA said on Tuesday.
The trio of exoplanets - worlds beyond the solar system - are all between the size of Earth and Neptune and closely orbit their stars.
"These are fairly average planets in the grand scheme of Kepler observations," said Elyse Incha, a senior at the University of Wisconsin-Madison. "But they're exciting because Kepler observed them during its last few days of operations. It showcases just how good Kepler was at planet hunting, even at the end of its life."
A paper about the planetary trio led by Incha was published Tuesday in the journal Monthly Notices of the Royal Astronomical Society.
Kepler was launched in March 2009. The mission's initial goal was to continuously monitor a patch of sky in the northern constellations Cygnus and Lyra. This long period of observations allowed the satellite to track changes in stellar brightness caused by planets crossing in front of their stars, events called transits.
After four years, the telescope had observed over 150,000 stars and identified thousands of potential exoplanets. It was the first NASA mission to find an Earth-size world orbiting within its star's habitable zone, the range of distances where liquid water could exist on a planet's surface.
When Kepler was retired in October 2018, it had aided the discovery of over 2,600 confirmed exoplanets and many more candidates, according to NASA.