There is Something Big Hiding on the Moon — What is it?

Under the South Pole-Aitken (SPA) basin, near the south pole of the Moon, something massive — and unknown — is hiding beneath the crust. A recently-discovered gravitational anomaly reveals the presence of a massive deposit of material sitting within the mantle of the Moon, undetected before now.

Baylor University researchers discovered this mass in the mantle of the Moon, between the crust and core of our planetary neighbor. The team theorizes it may be the remains of an asteroid that crashed long ago, forming the massive Aitken Crater.

The far side of the Moon, seen in a topgraphic map. Blue areas are lower elevations, while mountains are seen in red. The dashed circle highlights the site of the gravitational anomaly. Image credit: NASA/Goddard Space Flight Center/University of Arizona

“Imagine taking a pile of metal five times larger than the Big Island of Hawaii and burying it underground. That’s roughly how much unexpected mass we detected,” said Dr. Peter James, assistant professor of planetary geophysics in Baylor’s College of Arts and Sciences.

There’s No Crater Place

The South Pole-Aitken basin stretches 2,000 kilometers (1,250 miles) in length, from the Aitken Crater to the South Pole of the Moon, providing the feature with its name. If placed on the United States, this feature would reach from Washington, D.C. to Waco, Texas.

Around four billion years ago, a massive impact created an impact site on the Moon reaching more than eight kilometers (five miles) into the lunar surface, four…