The Two Faces of the Moon

The far side looks *nothing* like the side that faces us. After 55 years, we may finally know why.

“When you’re finally up at the moon looking back on earth, all those differences and nationalistic traits are pretty well going to blend, and you’re going to get a concept that maybe this really is one world and why the hell can’t we learn to live together like decent people.” -Frank Borman, Apollo 8

If you’ve ever looked up at the brightest object in the night sky, you’ve probably noticed how different some parts of it appear to be from others. And if you’ve ever taken a look at it through a telescope, especially if it’s not in its full phase, you’ve very likely noticed some remarkable features on its surface.

Image credit: Matija Pozojevic of http://www.hrastro.com/WaningGibbous_Moon/.

In particular, there are two main features about the Moon that you can’t miss:

1. That it’s heavily cratered, especially in the lighter-colored areas. Many cratered regions include small craters inside medium-sized craters inside giant craters. And…
2. That it has these dark areas known as maria (latin for “seas”), which have relatively few and mostly smaller craters…