Earth's moon is hiding a massive secret on its storied dark side. Deep below the South Pole-Aitken basin of the moon, which is the largest preserved impact crater ever found in the solar system, scientists have detected a massive anomaly of heavy metal lodged in the mantle that is apparently altering the moon's gravitational field.
According to a study published in the journal Geophysical Research Letters, the anomaly may be the heavy leftovers of the asteroid that crashed into the far side of the moon and it made a huge South Pole-Aitken crater around 4 billion years ago. However, all that researchers can say at this point is that the blog is massive, weighing around 2.4 quadrillions US tons or 2.18 quintillion kilograms.
"Imagine taking a pile of metal five times larger than the Big Island of Hawaii and burying it underground," lead study author Peter James, assistant professor of planetary geophysics at Baylor University's College of Arts & Sciences, said in a statement. "That's roughly how much-unexpected mass we detected."
James and his fellow researchers discovered the blob while comparing maps of the lunar topography with data collected by the Gravity Recovery and Interior Laboratory mission or GRAIL of NASA, it was an experiment in 2011 wherein two satellites orbited the moon in pairs, mapping the precise strength of its gravitational pull at various locations.
The GRAIL readings revealed something very heavy tugging down the bottom of the South Pole-Aitken crater by more than half a mile. Whatever it was, the offending anomaly was buried hundreds of miles below the surface of the moon.
In the new study, the scientists ran impact simulations to show that this underground debris could be the remnants of a heavy asteroid made of iron-nickel and that it got stuck part way to the lunar core.
"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," James said.
It measures about 1,553 miles or 2,500 kilometers wide, the South Pole-Aitken crater is already one of the moon's largest mysteries. It has the biggest impact crater in the solar system, it has a towering rim and it has a deep basin that contains the moon's highest and lowest elevations.
Scientists are not totally sure what the vast bowl of dusty rock is made of, but it could include some chunks of lunar mantle amidst the upper layers of crust and dust. China's ChangE-4 lander, which reached the far side of the moon this year, recently began analyzing soil near the crater, giving scientists their first peek at what the moon's innards are made of.
