Astronomy

making the moon

Researchers think the Moon was formed when Earth was struck by a Mars-sized body, known as Theia, early in the solar system’s history. These snapshots from a simulation published October 29 in The Astrophysical Journal Letters capture the terrifying and beautiful dynamics of such a collision. In the first three frames (top row), which cover a time frame of 30 minutes, the impactor gouges out a massive chunk of Earth, blasting debris into space. Over the following 10 hours (middle row), much of that debris rains back down to Earth, including huge fragments that have completed as much as half an orbit. Within 48 hours after the impact (bottom row), the remaining orbital debris has begun to form a disk of material that surrounds Earth. These remnants will eventually coalesce, forming…