There have been about 30 lunar meteorites found on Earth. On January 16, 2002, a lunar meteorite was found in Oman. The meteorite was the size of a fist and named Sayh al Uhaymir 169 after the district of Oman in which it was discovered. By studying its isotope chemistry, scientists have traced it back to the crater Lalande and the Imbrium basin located on the nearside, or earthside, of the moon.

The meteorite consists of impact-melt breccia, a common lunar rock type made from fragments of other rocks and welded together. The meteorite contains more thorium than any other lunar rock found on Earth. Scientists traced the rock to an area on the moon near Mare Imbrium that is rich in thorium.

The study shows the meteorite’s rocky breccia formed from a gigantic impact that occurred about 3,909 billion years ago that created the Imbrium basin. There was a second impact about 2.2 billion years ago that created the Lalande crater. A third impact about 200 million years ago created another crater close by. The fourth impact came less than 340,000 years ago that threw the meteorite into space. About 9,700 years ago, the lunar rock landed in the Omani desert.