It’s been more than half a century since the final Apollo mission left the Moon. But scientists are still learning from it. A few years ago, they started examining samples from Apollo 17 that hadn’t been touched before — a project that’s ongoing. They’re also analyzing observations made by instruments left on the Moon. That work says that lots of little tremors rattle the landing site.

Astronauts Gene Cernan and Jack Schmidt set up a quartet of special microphones to “listen” for moonquakes. The gear worked for about five years. Using techniques from AI, a recent study found more than 3200 quakes in just eight months of data.

Almost 400 of the tremors came from the direction of the base of the lunar module, Challenger. They were most common around sunrise and sunset, when the temperature changed in a hurry. Researchers say the tiny quakes probably were triggered by the lander as it heated and cooled, expanding and contracting in the process.

They’re still analyzing the other quakes. But many of them may have been triggered as minerals in the lunar dust expanded and contracted as well — tiny tremors that scientists are just learning about, decades after they took place.

The Moon is sliding through the constellation Leo right now. Tonight, the lion’s bright heart, the star Regulus, is close to the lower right of the Moon at nightfall, and closer below the Moon as they set, in the wee hours of the morning.

Script by Damond Benningfield