Earth is dotted with humongous, human-made structures that, to an alien eye, may be tell-tale signs of intelligent goings-on.

The possibility of life on other planets is one of the biggest mysteries in science. But what would happen if we actually ...

The Mars Moons eXploration spacecraft will fire its thrusters to maneuver into orbit around Mars (depicted in this digital ...

New images from the Mars Express spacecraft show ancient volcanic ash spreading across the Red Planet.

NASA's Curiosity rover snapped a series of peculiar polygons that look suspiciously like giant fossilized reptile scales.