giant-impact-hypothesis

Six Apollo landings returned 842 pounds of lunar material to Earth — 2,196 samples collected from six different sites across the nearside. Fifty-five years later, those rocks are still generating new discoveries, the laser retroreflectors are still in use, and the fundamental questions they raised about the Moon's violent origin have only deepened.

The giant impact hypothesis explains how a Mars-sized body called Theia struck the proto-Earth and formed the Moon ~4.5 billion years ago.

The Moon is more than a nightlight. It holds Earth's tilt steady, drives our tides, and may have made complex life possible.