According to recently published study Moon’s gravity is changing and a mysterious large mass of material, hidden beneath the largest lunar crater is to be blamed for it.
The mass was found under the Moon’s South Pole – Aitken basin, and may contain metal from the asteroid that crashed into the Moon and formed the crater, according to the researchers from Baylor University in the US.
The crater itself is oval-shaped, as wide as 2,000 kilometres and several miles deep. Despite its size, it cannot be seen from Earth because it is on the far side of the Moon.
To measure subtle changes in the strength of gravity around the Moon, researchers analysed data from spacecrafts used for the National Aeronautics and Space Administration (NASA) Gravity Recovery and Interior Laboratory (GRAIL) mission.
The dense mass is weighing the basin floor downward by more than half a mile, according to the research published in the journal Geophysical Research Letters.
Computer simulations of large asteroid impacts suggest that, under the right conditions, an iron-nickel core of an asteroid may be dispersed into the upper mantle (the layer between the Moon’s crust and core) during an impact.
Another possibility is that the large mass might be a concentration of dense oxides associated with the last stage of lunar magma ocean solidification.
James said that the South Pole-Aitken basin—thought to have been created about four billion years ago—is the largest preserved crater in the solar system.
While larger impacts may have occurred throughout the solar system, including on Earth, most traces of those have been lost.
James called the basin “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.”