When the Earth Had Two Moons: Cannibal Planets, Icy Giants, Dirty Comets, Dreadful Orbits, and the Origins of the Night Sky

In 1959, the Soviet Luna-3 station took the first photographs of the far side of the Moon. Even in poor resolution, the images stunned scientists: the reverse side looked like a huge expanse of mountain ranges, and not like the vast lava plains that cover the side visible from Earth. Subsequent missions confirmed this discovery with high-quality images. Why does the moon look the way it does, and ...