The Moon is a funny place. It's literally the closest astronomical object to us in the entire Universe, but in some ways we know surprisingly little about it. It's literally covered in craters, but for a long time their origin was a mystery. Until the 1870s, most scientists thought they were volcanic in origin and not from impacts (it wasn't until 1960 that Gene Shoemaker showed that some craters on Earth were impact events). That doesn't mean that there are no volcanoes on the Moon, though. The evidence isn't -- har-de-har -- rock solid, but this Lunar Reconnaissance Orbiter image is awfully tantalizing:
[Click to embiggen.] Located in Lacus Mortis -- the Lake of Death! -- this interesting feature certainly looks like a volcanic cinder cone. Impact craters don't generally have such gentle sloping on the inside wall, and such a large, shallow-sloped outside wall. The entire area around the ...
