This is a pretty neat picture taken by the Lunar Reconnaissance Orbiter: two craters, side by side:

[Click to impactenate.]

What’s cool about it is the obvious age discrepancy between the two craters. The Moon lacks water and air, but it has erosion nonetheless: micrometeorite impacts, solar wind, and even thermal stress cause by the month-long day night cycle slowly wears away at the surface. Old craters have a rounded look to them, while fresher craters are sharp-edged, and show the debris from impact.

The full-res image has a scale of just a meter per pixel, so a lot of the smaller boulders you see around the younger crater on the right are the size of cars. Both craters are roughly 300 or so meters across; you could walk briskly across them in a couple of minutes.

I noticed the young crater has an odd shape, non-circular, almost diamond-shaped. Then I looked at other, nearby craters, and saw the same thing, so it must mostly be due to lighting. However, there is a funny hillock just to the right of the crater, and the boulder field around it is not symmetric; there ...