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space rocks

The moon is quaking

For a long time, we've thought of the moon as one solid chunk of rock out in space. But recent analysis of data from NASA's Apollo missions is posing an interesting question that has geologists scratching their heads: What if it has tectonic plates just like the Earth?

In a study published in Nature Geoscience on Monday, scientists took a closer look at data of "moonquakes" picked up by seismometers at Apollo landing sites from 1969 to 1977. While these have been a mystery for a long time, the new analysis suggests that the moon is "actually more tectonically active than previously presumed," National Geographic reported.

This is a startling discovery because tectonic plates only shift, causing tremors and faults in the ground, when the interior of a planet — or satellite, in the case of the moon — is very hot. And since the moon is way smaller than the Earth, just a sixth of its size, we've long thought that its core is much cooler than ours. A cooled center would mean little to no tectonic activity, so scientists have been puzzling out what other factors could have caused a tremor that seemed like a moonquake.

But for this study, researchers simulated how often those other factors could align to cause something even resembling a moonquake, and ended up with odds of about 1 percent. So it's much more likely that the 28 major quakes picked up back in the 1970s were caused by tectonic activity, changing the way we think about the moon from here on out.

"The whole idea that a 4.6-billion-year-old rocky body like the moon has managed to stay hot enough in the interior and produce this network of faults just flies in the face of conventional wisdom," said Thomas Watters, one of the study's co-authors. That makes this new discovery "an amazing result."