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May 8, 2021
A quasi-satellite or quasi-satellite is a space object, the period of revolution of which around the Sun corresponds to the period of revolution of the planet around the Sun, i.e. objects are in orbital resonance 1: 1. This circumstance allows him to stay near the planet for some time.
The Latin prefix quasi means "like", i.e. the object is not a full-fledged satellite of the planet, only temporary, since after a while it leaves its orbit. The Earth had several quasi-satellites. These are asteroids of various sizes - from tens of meters to several kilometers, which remained in the orbits of the quasi-satellite for tens and hundreds of years.
The last quasi-satellite of the Earth was discovered in 2016. This is the asteroid (469219) Kamoalev (previously 2016 HO3), which, according to scientists, began to orbit in the quasi-satellite orbit about 100 years ago. Since the asteroid is with the Earth in an orbital resonance of 1: 1, and the distance between the planet and the asteroid varies quite insignificantly, from the point of view of the terrestrial observer it seems that it revolves not around the Sun, but around the Earth.
In fact, of course, this is not the case. Part of the asteroid's orbit is inside the Earth's orbit, and part is outside, so it either overtakes it when it is inside the Earth's orbit, then lags behind when it is outside, thus creating for the terrestrial observer the illusion of revolution around our planet.
Artist's illustration of the asteroid Kamoalev
Kamoaleva is a very small asteroid with a diameter of approximately 40-100 meters, from the Apollo group. Since it was discovered with the Pan-STARRS 1 telescope at the Haleakala Observatory in Hawaii, it was named in the Hawaiian word Kamoaleva, meaning "oscillating."
The asteroid Kamoalev, according to scientists, is the most stable example of a quasi-satellite of the Earth today. With a maximum distance from the Earth of 40 million km and a minimum distance of 14 million km, the asteroid will represent a quasi-satellite of the Earth for several more centuries, according to other sources - millennia.
ROSCOSMOS Press Release: https://www.roscosmos.ru/30987/
Moscow Planetarium: https://www.roscosmos.ru/tag/moskovskiy-planetariy/
Images, Text, Credits: ROSCOSMOS/Moscow Planetarium/Orbiter.ch Aerospace/Roland Berga.
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