Earth may have at least 6 ‘minimoons’ at any given time. Where do they come from? | Live Science

Half a dozen fragments of the moon may briefly orbit Earth at any given time, before moving on to circle the sun, new research suggests — but the minimoons’ small size and quick pace make them challenging to spot.

When objects collide with the moon, they send up a shower of material, some of which manages to escape into space. Although there may be an occasional large chunk, most are fast-moving and smaller than 6.5 feet (2 meters) in diameter. The bulk of the lunar material falls into orbit around the more gravitationally attractive Sun. But some of the debris may occasionally be pulled into an orbit around Earth before returning to circle the sun, researchers explained in a study published in the journal Icarus.

It’s “kind of like a square dance, where partners change regularly and sometimes leave the dance floor for a while,” Robert Jedicke, a researcher at the University of Hawaii and lead author of the study, told Space.com by email.

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‘Stepping stone to Mars’: Minimoons may help us become an interplanetary species, says MIT astrophysicist Richard Binzel | Live Science

More than 30,000 asteroids are traveling on paths that bring them close to Earth. Some are giant boulders with the potential to smash into our planet, and others are little rocks known as minimoons moving harmlessly alongside Earth. For half a century, Richard Binzel, an astronomer at Massachusetts Institute of Technology (MIT), has dedicated his career to studying them.

Live Science spoke with Binzel about minimoons and how these little rocks could eventually help humanity take its first trip to Mars.

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