Lunar meteorite

A lunar meteorite is a special kind of meteorite that comes from the Moon. These space rocks are thrown off the Moon when something, like another space rock, hits it really hard. This sends pieces of the Moon flying into space, and sometimes those pieces later fall to Earth.

When a meteorite hits the Moon, it can create a flash of light or a shadow that people on Earth can sometimes see. These events are called transient lunar phenomenon. Scientists study lunar meteorites to learn more about the Moon’s surface and its history.

Lunar meteorites are very rare and valuable for scientists because they give us pieces of the Moon to study. By looking at these rocks, we can discover important information about how the Moon formed and changed over time.

Discovery

In January 1982, John Schutt found a special meteorite in Antarctica during an expedition for the ANSMET program. The meteorite, called Allan Hills 81005, was sent to Washington, DC. There, Brian Mason, a scientist at the Smithsonian Institution, noticed it was different from other meteorites and looked like rocks brought back from the Moon by the Apollo program.

Later, Japanese scientists found another lunar meteorite, Yamato 791197, in Antarctica in 1979. By July 2019, 371 lunar meteorites had been discovered. These meteorites come from the Moon and have been found mostly in deserts, especially in Antarctica, northern Africa, and the Sultanate of Oman. None have been found in North America, South America, or Europe. Scientists determine they come from the Moon by comparing their composition to samples collected by Apollo missions.

Transfer to Earth

Most lunar meteorites come from the Moon. They are sent away from the Moon when other space rocks crash into it, creating craters a few kilometers wide or smaller. We do not know exactly which craters these meteorites came from, but some think a special meteorite named Sayh al Uhaymir 169 might have come from a crater called Lalande on the side of the Moon that faces Earth.

Scientists have studied these meteorites and found that they all left the Moon in the last 20 million years. Most of them left in the past 100,000 years. After leaving the Moon, many of these space rocks start moving around Earth and eventually fall down because of Earth's gravity. Some of the meteorites are sent into orbits around the Sun. They stay in space for a longer time, but they will eventually come close to Earth's path and land on our planet.

Scientific relevance

The six Apollo missions collected samples only from one part of the Moon, which is different from the rest of the Moon. Lunar meteorites, however, come from random places on the Moon, giving us a better picture of its surface. About half of these meteorites likely came from the far side of the Moon, which we haven’t visited.

When the first lunar meteorite was found in 1982, it helped scientists think that rocks from Mars might also reach Earth. Some scientists even wonder if we might find very old rocks from Earth on the Moon, since Earth’s surface changes over time and some rocks might not survive here.

Observation history

About one in every thousand newly found meteorites comes from the Moon. Most meteorites we find are from the asteroid belt. In the early 1800s, many scientists thought all meteorites came from the Moon. Some people still think small glass pieces called tektites might also come from the Moon, but most scientists do not agree with this idea.

Private ownership

Lunar meteorites found in Africa and Oman are the main way for people to own pieces of the Moon. Rocks brought back by the Apollo missions belong to the United States government or other countries that received them as gifts. Similarly, meteorites collected by the U.S. and Japan in Antarctica are kept for research and education. While there is no law stopping private ownership of these rocks, the U.S. government has never sold any to the public. Even special plaques with Moon rocks given to astronauts and Walter Cronkite in 2004 still kept the rocks under NASA's ownership. Most samples from the Luna 16 probe are also not available for private ownership, though three very small pieces were sold at an auction in 1993.