For billions of years, our celestial neighbour has been absolutely bombarded by asteroids and comets, and the assault has left behind a heavily pockmarked surface. The largest and oldest known impact site on the Moon is the South Pole-Aitken basin, stretching across nearly 1,250 miles of the far side of the Moon. Thanks to new research, scientists have dated the impact to a period between 4.32 and 4.33 billion years ago.
A research team led by scientists at the University of Manchester determined the age of the basin by analysing a lunar meteorite known as Northwest Africa 2995. Found in Algeria in 2005, it contained uranium and lead that was dated to this period.
“For decades there has been general agreement that the most intense period of bombardment was concentrated between 4.2 and 3.8 billion years ago,” said Joshua Snape, a researcher at the University of Manchester.”But now, constraining the age of the South-Pole Aitken basin to 120 million years earlier weakens the argument for this narrow period of impact bombardment on the Moon.”