Astronomers have identified an extreme exoplanet, LTT 9779 b, that is reshaping our understanding of planetary atmospheres.

Online chatter and a frenzy of media coverage has tended to make a big deal of allegedly rare "planetary alignments" and "planet parades" gracing our night skies. The hoopla has culminated this month ...

It's certainly not a small island: It's about three times the size of Texas. But on most maps, Greenland looks almost as big as the entire continent of Africa. In fact, it's 14 times smaller than ...

The shape of a planet's orbit is one of its fundamental properties, along with its size and distance from its host star.

But Charon was half the size of Pluto itself, so big that the Pluto-Charon combination are sometimes referred to as a double planet, according to NASA. In August 2006 the International ...