Add Yahoo as a preferred source to see more of our stories on Google. A small mare ridge in Northeast Mare Imbrium taken by the Lunar Reconnaissance Orbiter Camera. (CREDIT: NASA / GSFC / Arizona ...

Low, winding ridges run across the Moon’s dark plains like faint seams in cooled wax. They are easy to miss in a wide photo. Up close, they look like the surface has been gently pushed from below. A ...