This short film charts the story of the Earth's single natural satellite - the Moon. The most widely accepted theory is that, shortly after it formed, the proto-Earth was struck at an oblique angle by another protoplanet, roughly the size of Mars. Astronomers call this interloper Theia. Debris from the impact was flung into space. Some of this escaped, but a lot of it remained and formed an orbiting ring of debris around the Earth. The material in this ring eventually coalesced, very quickly, to form our Moon.