Non-Asteroidal Meteorites "Regular" meteorites from the Asteroid Belt have crystallisation ages corresponding to the formation of the Solar System, and so are around 4560 to 4570 Myr old. There are, however, two groups of meteorites with younger ages, indicating that they formed after the main planet-building episode of Solar System history. The first of these groups comes from the Moon, and the second is from Mars. The mechanism that removed material from the Moon and Mars is one of impact: both the Moon and Mars are covered in craters caused by asteroid impact. If the impactor hits the lunar or martian surface at an appropriate angle and with sufficient velocity, then material ejected during the impact can escape from the surface, and fall towards the Sun. In some cases, the material is picked up by the Earth as lunar or martian meteorites. Lunar meteorites The meteorites that come from the Moon (about 20 in total) can be compared directly to material brought back from the Apollo and Luna missions. The lunar meteorites have the same mineralogy, chemistry and isotopic composition as the Apollo and Luna samples. There is little doubt that these meteorites were removed from the Moon during a cratering event. Lunar meteorites extend the range and diversity of materials available for study from Earth's only natural satellite. Martian meteorites Currently, there are 25 specimens that differ from asteroidal meteorites, and are believed to emanate from Mars; they are known as the SNC meteorites, after the type specimens (Shergotty, Nakhla and Chassigny) of the three main sub-groups. Martian meteorites assist in interpretation of magmatic and fluvial processes on Mars, and have stimulated studies into the potential existence (extinct or extant) of life on Mars.

MAC88105 - A large lunar meteorite found at the MacAlpine Hills Icefield in 1989. The black cube in the lower left is 1 cm across.