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Thursday, September 16, 2021

CONTEXT: The Strange Orbit of “Earth's Second Moon”

The asteroid 3753 Cruithne is in an Earth-crossing orbit (thus classified as an “Aten asteroid”) with an orbital period identical to that of Earth. Its elliptical orbit takes it as far as 1.51 astronomical units (AU) (the mean distance between the Earth and Sun) from the Sun and as close as 0.5145 AU. This means that its position traces out a closed path around the Earth and, in the Earth's reference frame, appears to orbit Earth in a D-shaped “kidney bean” orbit, although it is not gravitationally bound to the Earth and thus not a true satellite. Although subject to perturbations by other planets over the very long term, this orbit is believed to be stable for millions of years into the future.

Posted at September 16, 2021 11:26