Hot Rain

A giant storm complete with lightning and rain rages above the surface of a brown dwarf in this artist's concept. The atmosphere is so hot, though, that the rain consists of droplets of molten iron or hot sand, not water. A brown dwarf is a "failed star" -- an object that's heavier than a planet but not heavy enough to ignite nuclear fusion in its core and shine as a star. Yet their gravity squeezes them so strongly that it generates intense heat. Several recent studies have demonstrated that clouds top the atmospheres of many brown dwarfs, sometimes producing storms that are tens of thousands of miles across. [NASA/JPL/Univ. Western Ontario/Stony Brook Univ.]