| Astrophysics (Index) | About |
A quasi-satellite is a body whose orbit keeps it near another orbiting body (its quasi-host) but the two are generally orbiting a third body, no more than loosely attached to each other. An example could be asteroid that is generally close to Earth though both are orbiting the Sun. The general scenario is a 1-1 orbital resonance but with differing orbital eccentricity. The quasi-satellite may sometimes approach its quasi-host, and may even encircle it, but not in a clear orbit as does the Moon around Earth. A quasi-satellite is beyond the Hill radius of its host, and may well drift away in a matter of years (rather than millions or billions of years). In the last two decades, a few Earth quasi-satellites have been discovered, a current (2022) example being 469219 Kamo'oalewa, a near-Earth object with a length of about 40 meters which comes within 0.03 AU of Earth.