Mini moon trajectory. Credit: Javier Roa Vicens.
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Earth has only one moon, the Moon, but it does have smaller objects that visit the planet, complete a few orbits, and then head off into space again. Astronomers have detected four of these objects so far and performed spectroscopic analyses on them, analyzing their surface composition. They found that some of these minimoons have a composition that's very similar to the Moon, pointing to it as a major source of these temporary satellites and not the asteroid belt.
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