A new super-Earth has been discovered in the habitable zone of a binary system thanks to the effort of citizen scientists looking through the data of the Kepler telescope. The exoplanet is known as K2-288b and is located 226 light-years away.

The system of K2-288b is made of two stars separated by roughly six times the distance between the Sun and Saturn. The larger one is about half as massive as the Sun, while the smaller one is about one-third. The new planet orbits the smaller one, which is classified as a cool M star. The findings are reported in The Astronomical Journal.

K2-288b is roughly 1.9 times the size of Earth and it orbits its star in 31.3 days. It is much closer to its star than any planet in the Solar System, but its star is much dimmer than our own. This puts this super-Earth in the habitable zone, where liquid water might exist. At the moment, however, we don’t know if it’s a rocky planet or if it's gassy.

"It's a very exciting discovery due to how it was found, its temperate orbit, and because planets of this size seem to be relatively uncommon," lead author Adina Feinstein, a University of Chicago graduate student, said in a statement.

Feinstein presented this work at the 223rd meeting of the American Astronomical Society in Seattle this week. The discovery happened when she and undergraduate student Makennah Bristow of the University of North Carolina Asheville, worked as interns with astrophysicist Joshua Schlieder at NASA's Goddard Space Flight Center.

The Kepler mission has ended after it ran out of fuel last October but scientists continue to comb through its data. Software is employed to find potential candidates, but often the human eye is needed to distinguish between signal and noise. Everyone can help with this challenging task and that’s how the planet came to the attention of the team of astronomers. Citizen scientists taking part in the Zooniverse’s Exoplanet Explorer project discovered the signals that suggested the presence of a potential planet.

The team conducted a series of follow up observations with ground-based and space telescopes. The planet seems to fit well in the category of intermediate mass planets. It has recently been discovered that intense stellar radiation can evaporate the atmosphere of Neptune-sized planets near their stars, separating the population of hot and temperate planets into small and rocky or gas giants, so the next step is to see which this is.