This picture of the Earth and Moon in a single frame was taken by the Galileo spacecraft from about 3.9 million miles away.

Antarctica is visible through clouds (bottom). Also the Moon’s far side is seen; the shadowy indentation in the dawn terminator is the south pole Aitken Basin. Therefore one of the largest and oldest lunar impact features. The distance and frame in this shot is incredible. The Moon is thought to have formed about 4.51 billion years ago, not long after Earth. The most widely accepted explanation is that the Moon formed from the debris left over after a giant impact between Earth and a Mars-sized body called Theia.