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Exploradio Origins sparks ideas and conversation with its unique and engaging 90 second nutshell approach. Each episode highlights the work of one of the more than 200 fellows at the Institute for the Science of Origins at Case Western Reserve University.

Exploradio Origins: The Moon as a Dark Matter Detector

A view of the full moon photographed from the Apollo 11 spacecraft during its trans-Earth journey homeward.

We all enjoy the moon on a clear night, but what if it could do more for us?

Glenn Starkman, professor of physics at Case Western Reserve University wonders if the moon could be a detector for dark matter--the stuff that causes the extra gravity needed to hold galaxies together as they spin.

It turns out that finding it is….hard.

“For a long time people have thought that dark matter was particles that would fly through matter, but another possibility is that dark matter comes in really big chunks and if that’s true then there wouldn’t be very many of them," Starkman said.

...you'd need a really big detector. One of the best ones could be the moon.

"That means you’d need a really big detector. We probably can’t build a detector that’s big enough. So we have to look for one. One of the best ones could be the moon.”

These dark matter chunks would be made of protons and neutrons. But they would be much more densely packed than they are in normal matter.

This type of dark matter would fly right through the moon, kind of like shooting a bullet through Jell-O.

"What do you expect to see?" Starkman ponders. "You expect to see a hole on one side. You expect to see the Jell-O jiggle. And on the other side you expect the Jell-O to go flying out in a big splat. Which we can look for: we can look for the splats, we can look for the holes and we can try to listen for the Jell-O wiggling."

So the next time you find yourself looking up at the moon, remember it could be our very own dark matter detector.

Exploradio Origins is a weekly feature produced in conjunction with the Institute for the Science of Origins at Case Western Reserve University. Tune in to 89.7 WKSU every Thursday afternoon during All Things Considered to listen to Exploradio Origins. You can find each segment posted online after it airs. Explore all the segments here.