NASA’s planet-hunting Kepler mission has found its most Earth-like planet yet, confirming its first planet in the “habitable zone,” where liquid water could exist on the surface. Called Kepler-22b, the planet is just over twice the size of Earth; if the greenhouse effect works there in a similar way to how it does here on Earth, NASA’s team predicts Kepler-22b’s surface temperature could be a comfortable 22 degrees Celsius (72 degrees Fahrenheit). While the team hasn’t yet confirmed whether the planet has a rocky surface, it orbits a star similar to our own sun. On top of this exciting find, NASA’s Kepler mission has also discovered more than 1,000 new planet candidates, which almost doubles its original count. Ten are close in size to Earth and in the habitable zone of their suns, although they still have to be confirmed as actual planets. “This is a major milestone on the road to finding Earth’s twin,” says Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington.
Maclean’s reported on the Kepler mission in February, when NASA first announced Kepler had discovered 1,235 potential planets, including 54 in the habitable zone. Kepler-22b is one of these 54. As the mission continues, we’ll learn whether planets like Earth are relatively common, or rare.