Optical proof of a tiny companion orbiting supergiant star Betelgeuse is hard to come by. Hubble just spotted new evidence.

An inexplicably hot, fast-growing cluster of galaxies in the early universe has scientists questioning theories of galactic evolution.

Daily life increasingly depends on systems of satellites orbiting Earth. As fleets proliferate, ever greater numbers of expired units will hurtle back toward the surface. Decommissioned satellites ...

It's not entirely clear how neighboring planet Mars went from a presumably life-supporting planet to a place as dead as all others in the solar system. We do know, however, that whatever water and ...

A new study suggests lunar soil contains elements that solar wind transported to the moon from Earth’s atmosphere, solving a long-standing astronomy puzzle.