NASA’s Kepler mission has confirmed its first planet in the habitable zone, the region where liquid water could exist on a planet surface. Kepler also has discovered more than 1,000 new planet candidates, nearly doubling its previously known count. Ten of these candidates are near Earth size and orbit in the habitable zone of their host star. The newfound planet in the habitable zone is called Kepler-22b. It 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.
Kepler-22b is located 600 light-years away. While the planet is larger than Earth, its orbit of 290 days around a sun like star resembles that of our world. The planet’s host star belongs to the same class as our sun, called G-type, although it is slightly smaller and cooler. Of the 54 habitable zone planet candidates reported in February 2011, Kepler-22b is the first to be confirmed.