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Why do some meteorites come from the Moon or Mars?
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Small body
Asteroid Ida and its satellite, Dactyl, photographed by the Galileo spacecraft on August 28, 1993, from a distance of about 10,870 km (6,750 miles). Ida is about 56 km (35 miles) long and shows the irregular shape and impact craters characteristic of many asteroids. The Galileo image revealed that Ida is accompanied by a tiny companion about 1.5 km (1 mile) wide, the first proof that some asteroids have natural satellites.
Meteorites originating from the Moon and Mars are not fragments of asteroids, which constitute the vast majority of meteorites found on Earth. Instead, these rare specimens are pieces of planetary or lunar surface material that were ejected into space by violent impacts.123
After being blasted off their parent bodies, these fragments traveled through space before eventually falling to Earth. Scientists confirmed their origins through several lines of evidence:13
- Martian Meteorites: These rocks are identified as volcanic in origin and often possess young crystallization ages—ranging from 150 million to 1.3 billion years—indicating they formed on a geologically active planet rather than an ancient asteroid. The most definitive proof came from the discovery of trapped gases within these meteorites that match the unique composition of the Martian atmosphere measured by space probes.13
- Lunar Meteorites: These fragments resemble the various rock types collected during the Apollo and Luna missions, confirming their origin from the Moon.1