When, for the first time ever, astronomers confirm the existence of an Earth-size planet in the habitable zone of a sunlike star, the spacecraft that makes such a moment possible is almost an afterthought. As December got under way, NASA revealed that its Kepler space telescope had detected telltale signs of a planet in the presumably habitable zone of a star 600 light years from Earth.
Given its proximity to that star and given the star's size and heat, the planet Kepler-22b could be balmy indeed. "If the greenhouse warming were similar on this planet, its surface temperature would be something like 72 Fahrenheit, a very pleasant temperature here on Earth," NASA researcher Bill Borucki said. That's hardly the only if. NASA still needs to determine, for instance, whether Kepler-22b is rocky like Earth, rather than gaseous or liquid.