The Lunar Reconnaissance Orbiter has been circling the Moon since June 2008, taking incredibly high-resolution images of our neareast astronomical neighbor. It's photographed craters, ancient lava beds, mountains, and cliffs, but this image really stands out to me: it shows a house-sized boulder which rolled down a hill and landed inside a crater like a golf ball at a Putt-Putt course!

The left side of the picture is a hill which goes downhill to the right. The landscape flattens out in the middle, and you can see bits of rubble and debris from landslides at the point where they meet. A billion years ago or more, something must have dislodged that gigantic rock, setting it rolling down the hill. Not being round, it bounced along in the Moon's 1/6th gravity, leaving ruts dug into the powdery surface. It slowed when it hit the flatter surface, and almost came to a stop just past that 60-meter (200 foot) crater. But it must have teetered backwards (see how that last rut goes past the rock?) and then slid down into the crater itself, where it finally came to a stop.

It's easy to think that the Moon is mostly dead and unchanging, but when you look more closely - really, really closely - you'll see evidence of a dynamic world, with subtle beauty and fascinating structures. And we've only explored a tiny fraction of it. What else is there to see in the remaining 36 million square kilometers?

Get the higher-res version here.

Image credit: NASA/GSFC/Arizona State University