Citizen scientists have found an exoplanet that was overlooked in previous analyses of data from NASA's Kepler satellite.
The planet, about 700 parsecs away, is roughly four times as massive as Earth, according to Joseph Schmitt of Yale University in New Haven, Connecticut, and his colleagues — including three users of the Planet Hunters website, which crowdsources analysis of Kepler data. The planet, named PH3 c, also has a low density, suggesting a substantial atmosphere of hydrogen and helium gas.
The volunteers spotted dips in the brightness of the planet's host star as the planet moved in front of it every 66 days. The gravitational pull of other planets caused the timing of these transits to vary by 10 hours, allowing the planet to elude Kepler's automated search. The planet is the third confirmed find by the Planet Hunters community.