NASA's Kepler mission has confirmed its first planet in the "habitable zone," the region where liquid water could exist on a planet’s surface
NASA - NASA's Kepler Confirms Its First Planet in Habitable Zone of Sun-Like Star
The newly confirmed planet, Kepler-22b, is the smallest yet found to orbit in the middle of the habitable zone of a star similar to our sun. The planet is about 2.4 times the radius of Earth. Scientists don't yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition, but its discovery is a step closer to finding Earth-like planets.
NASA - NASA's Kepler Confirms Its First Planet in Habitable Zone of Sun-Like Star
サイズは地球の2.4倍、ハビタブルゾーンの真ん中にあることが判明した中では最も小さい。
多分、液体の水があるということがポイントだが、主成分が、岩石か、ガスか、氷かはまだ分からない。
これだけだとまだなんとも言えないが、一つ見つかればどんどん見つかるのがこの手の探索の常。存在率とか分かるのはもう少し先だろうけれど、どれくらいになるかな。
