The moon’s base seems to have a large gravitational anomaly, researchers at Baylor University in Texas reported.
After examining NASA missions’ data, researchers evaluated the subtle changes in the strength of gravity around the moon, discovering that it could be the result of a mass of metal, originating from deep space, being buried beneath the moon's surface and weighing it down.
The alleged metal is located on the moon's South Pole-Aitken basin, a 2,000km wide and 13km deep crater at the bottom of the planet, believed to be the largest crater in the solar system.
"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," the study's lead author Dr Peter James stated.
"When we combined [the gravitational data] with lunar topography data from the Lunar Reconnaissance Orbiter, we discovered the unexpectedly large amount of mass hundreds of miles underneath the South Pole-Aitken basin," Dr James said.
"One of the explanations of this extra mass is that the metal from the asteroid that formed this crater is still embedded in the moon's mantle. Whatever [ the dense mass] is, wherever it came from is so heavy it is actually weighing the basin floor downward by more than half a mile,” Dr James noted.
"We did the math and showed that a sufficiently dispersed core of the asteroid that made the impact could remain suspended in the moon's mantle until the present day, rather than sinking to the moon's core," Dr James added.
Scientists also gave way to other theories, with some suggesting that dense metals had pooled when the molten moon began to solidify billions of years ago.
The South Pole-Aitken basin was created around four billion years ago, Dr James noted.
“The moon's basin is one of the best natural laboratories for studying catastrophic impact events, an ancient process that shaped all of the rocky planets and moons we see today,” Dr James described.