Most people think the Moon is a silent, still place, but it’s actually shrinking a tiny bit every year. As the inside of the Moon cools, it contracts—kind of like a dried-up apple—and that causes the surface to crack and shift. Over millions of years, the Moon has shrunk by about 45 meters in diameter. That’s a big change if you have a few hundred million years to wait, but it’s only about 1–2 millimeters per year—way too slow for anyone to notice.
But here’s the surprising part: when the Moon’s crust cracks, it can create powerful “moonquakes.” Some of these quakes are as strong as a magnitude 5 earthquake on Earth. On our planet, that’s enough to rattle houses and break dishes. On the Moon, these quakes can last longer and shake even more because there’s no air or water to slow down the vibrations.
This is a big deal for NASA, especially now that they’re planning to send astronauts to live and work on the Moon with the Artemis program. To keep astronauts safe, NASA is doing a lot of planning:
• Choosing Safe Spots: Scientists study maps of the Moon to find places with fewer cracks and faults, so bases are less likely to get hit by a big quake.
• Building Strong Structures: Engineers design lunar bases and landers to survive shaking, using special construction techniques like they do in earthquake zones on Earth.
• Installing Sensors: NASA will set up seismometers—special “earthquake detectors”—to watch for moonquakes near lunar bases. This way, they can warn astronauts if the ground is about to shake.
• Smart Scheduling: Since some moonquakes happen at certain times in the Moon’s orbit, NASA might plan spacewalks and building projects during safer periods.
The Moon may look calm, but beneath the surface, it’s still changing. Thanks to new research and careful planning, astronauts heading to the Moon with Artemis will be ready for whatever our nearest neighbor throws at them.
