Arlington, Va.–A team of astronomers has announced the discovery of some of the smallest planets yet detected beyond our solar system: two worlds that represent a new category of extra-solar ...

Discover the order of planets in the solar system. From Mercury to Neptune, explore our solar system and learn more about our cosmic home.

The planets in our solar system are a veritable rainbow of colors. But what makes them take on all their various hues, and why does each one look so different?

That's just one aspect of the atmosphere on XO-3b, one of a class of exoplanets (planets outside our solar system), known as hot Jupiters.