There is an anomaly under the largest crater on the Moon. The mysterious metal mass just discovered under the largest crater of the Moon could come from the crash with an asteroid, which occurred about 4 billion years ago.

What’s in the depths below the largest crater of the Moon? It was discovered by researchers at Baylor University, who on the pages of Geophysical Research Letters, say they have just identified a mysterious and enormous mass of material under the South Pole-Aitken basin, a huge meteor crater about 2500 kilometers in diameter located on the hidden side of our satellite, or the hemisphere perennially opposite to the Earth. According to the researchers, this mass could contain a metal from a large asteroid that crashed on the Moon about 4 billion years ago, subsequently forming this crater.

What’s under the largest crater on the Moon?
Image: NASA – Goddard Space Flight Center – University of Arizona

“Imagine taking a mass five times larger than the Island of Hawaii and burying it underground, it’s about the mass we’ve just discovered,” study author Peter B. James explained. To understand this, the researchers reviewed the data coming from the probes of the Gravity Recovery and Interior Laboratory (Grail) mission of NASA to measure the changes in the gravitational field of the Moon and thus understand its internal structure.

“When we combined this information with data on the lunar topography of the Lunar Reconnaissance Orbiter , we discovered an unexpected amount of mass extending hundreds of kilometers (over 300 km deep, ed) under the South Pole basin” commented James. “One of the possible explanations for this extra mass is that the metal of the asteroid that formed this crater is still embedded in the mantle of the Moon.” In fact, computer simulations suggest that, under certain conditions, an iron-nickel core of an asteroid can, during impact, be incorporated  into the mantle, the layer between the crust and the nucleus, of the Moon.

This mass, researchers say, of whatever nature, is pushing the bottom of the South Pole-Aitken basin down. “Our calculations showed that the nucleus of an asteroid could remain suspended in the mantle of the Moon until the present day, rather than sinking towards the core of the Moon,” explained James. Another hypothesis, the author points out, could be a concentration of titanium oxides, associated with the last phase of the solidification of the lunar magmatic oceans.

“This crater”, concludes the author, “represents one of the best natural laboratories to study the events of catastrophic impact that have shaped all the rocky planets and the moons that we can observe today”.