NASA says "cross-bedding" in the layers of this Martian rock is proof that water moved on Mars, leaving waves or ripples of loose sediment. The image is from a site at Mount Sharp that NASA calls "Whale Rock."
A blast from the past: Using data from four telescopes, NASA created this image of the first documented sighting of a supernova, made by Chinese astronomers in 185 A.D.
The Orion capsule is poised to make its first test flight Thursday. If all goes as planned, the unmanned vehicle will orbit Earth twice before splashing into the Pacific Ocean.