Planet in the "Habitable Zone"

Scientists announced yesterday that the recently discovered planet "Kepler 22-b", orbiting a star about 600 light years from Earth, is confirmed as being in the "habitable zone" of its parent star. The habitable zone of Sol extends from just outside Venus to a bit outside of Mars. It is the zone where temperatures should permit the existence of liquid water.

Three transits of this planet have now been observed. The body is slightly less than 2-1/2 Earth masses. The "sun" it orbits is 25% smaller than our own, so the fact that this new planet is somewhat closer to its star than we to ours is not of consequence in terms of heat and light received. Its orbital period (year) is 290 Earth days.