The Cliffs of Charon

NASA released a photo of Pluto's moon Charon the other day, and in the article about it they mentioned something I hadn't thought of when I first saw the close-up photos of Charon last year. And I really should have! First, as you can see in the above photo, Charon looks like nothing so much as Frankenstein's moon: a satellite cobbled together from bits of others and slapped together rather haphazardly. The southern hemisphere is smooth, the northern rugged, the great blotch of Mordor staining t...