A milestone find by the Kepler mission: a planet a little over twice the size of Earth, situated in the Goldilocks zone of its star where liquid water can exist at the surface. Which by extension means that, if this planet is terrestrial and has water, there’s the possibility of life as we know it.
Evidence for others has already been found by Kepler, but this is the first confirmation. The planet, Kepler-22b, is also only about 2.4 times the radius of Earth, the smallest planet found in a habitable zone so far, and orbits its star, Kepler-22, in 290 days. It is about 600 light-years away from Earth, and Kepler-22 is only slightly smaller and cooler than our own Sun. Since its mass is not yet known, it is not known yet if it is a rocky or gaseous planet, but its discovery is a major step toward finding Earth-like worlds around other stars.
It’s apparently also found another 1094 more exoplanet candidates, nearly doubling the exoplanet count last reported in February to 2326. And 207 of them are near Earth-sized, with another 680 being super-Earths. We’re finding planets so close to our own size, around stars so close to our own, which means our data collection methods must have improved significantly in this nascent field of space exploration even just during the Kepler mission. Now, if only we can find another Earth before we use this one up!