Five Things to Know About the Moon
- Earth’s Moon is a cornerstone of planetary science. Without plate tectonics or weather to erase evidence of its past, our closest neighbor in space preserves a record of the geologic history that has shaped our solar system – including our own planet.
- Evidence suggests that, about 4.5 billion years ago, a Mars-sized object crashed into early Earth. The debris from this impact likely formed the Moon.
- Moonquakes shake it. Compared to Earth, the Moon is a quietly active world. Tidal forces, meteoroid impacts, and thermal changes in rock near the surface all trigger seismic disturbances.
- The coldest temperatures in the solar system have been recorded at the Moon’s poles. Some polar craters, darkened by permanent shadows, harbor hidden water ice.
- Twelve humans have walked on the Moon (all astronauts in NASA’s Apollo program in the 1960s and 1970s). Plans are now under way for humans to return to the Moon through NASA’s Artemis program.