In May 2017 after looking at the new information that was posted on Exoplanet Explorers - which allows the public to look at Kepler's K2 observations to try and find new transiting planets - they finally found that third transit.
A year ago at the American Astronomical Society meeting, it was announced that citizen scientists helped discover five planets between the size of Earth and Neptune around star K2-138, the first multiplanet system found through crowdsourcing.
But there's a reason it's so super, it's about twice the size of regular Earth and astronomers say as it's located in our "habitable zone", might even contain life - also, the other option for a name is K2-288Bb, which isn't the catchiest.
Furthermore, the planet could be gas-rich like Neptune or rocky like Earth. "But here we were lucky, and can now study this one in more detail".
K2-288Bb lies within its star's habitable zone, meaning it is possible for it to hold liquid water.
A second exoplanet may also be in the same star system, but we'll have to wait for follow-up observations to confirm it.
Citizen scientists have discovered an exoplanet twice the size of Earth located 226 light-years from Earth. The discovery is unique for a number of reasons - not least of which is that it was made by amateur astronomers - but the biggest surprise for scientists was its size.
Dragomir said: "It has the coolest surface temperature of a transiting exoplanet around a star brighter than 10th magnitude, or about 25 times fainter than the limit of unaided human vision".
"We think this planet wouldn't be as gaseous as Neptune or Uranus, which are mostly hydrogen and really puffy". Among planets that orbit close to their stars, there's a curious dearth of worlds between about 1.5 and two times Earth's size. The exoplanet's signature was discovered among data collected by NASA's Kepler space telescope. That's actually quite cool, considering how close the planet is to its star. Over the course of two years, the four wide-field cameras on board will stare at different sectors of the sky for days at a time.
When the researchers looked through the HARPS data, they discovered a repeating signal emanating from HD 21749 every 36 days. "TESS found as many in its first month". Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA's Ames Research Center in California's Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore.