An asteroid impact 4.3 billion years ago caused havoc in the moon’s mantle, explaining why one side of the moon has more craters than the other. A recent study supports this theory.
Per the International Astronomical Union, the moon has more than 9,000 visible craters as a result of a bombardment of strikes from meteors, asteroids, and comets spanning billions of years. There is some variation in the distribution of these craters over the lunar surface. Due to tidal locking, humans on Earth never see the distant side, which has a far greater concentration than on the observable side. Unlike the far side of the moon, which is coated in lunar maria, the near side has fewer holes as the surface is coated in large areas of solid lava. Lava fields may have concealed craters that would normally have characterized the moon’s nearside. The craters on the furthest side of the moon are still visible because there are no lunar maria there.
In the wake of a cataclysmic collision 4.3 billion years ago, scientists have long believed that the lunar maria originated. South Pole–Aitken basin (SPA) is the biggest crater on the moon and the second-largest known impact crater in the solar system, with a maximum diameter of 1,600 miles (2,574 kilometers) and a peak depth of 5.1 miles (8.0 kilometers). However, until today, scientists were stumped as to why lava fields could be found solely on the nearside of the moon.
The nearside of the moon was the only part of the moon damaged by the SPA impact, according to the latest research. According to the new research, computer models show that the SPA impact caused a mantle heat plume that drove radioactive materials toward the crust. There are several different ways the impact might have occurred, including direct strikes and glancing blows, but researchers discovered that the mantle hits would have only harmed the moon’s close side irrespective of how the asteroid struck.