Rather than a cold, featureless ball on the fringes of the solar ... and valleys. Charon, its biggest of five moons, was discovered in 1978 by the U.S. Naval Observatory. At about 750 miles ...

The biggest and oldest of these scars is a monster crater, one of the largest, not just on the Moon, but in the entire Solar System. The South Pole-Aitken basin covers nearly a quarter of the Moon ...