A near-Earth asteroid turned out to be a debris of the Moon
Asteroid (469219) Camoaleva is a quasi-satellite of the Earth. So called space objects that are in orbit around the Sun, but remain relatively close to Earth due to the fact that their orbital period is close to the Earth. Quasi-satellites are often difficult to observe with telescopes because they remain reflecting little sunlight toward Earth.
Kamoaleva was discovered in 2016 by the PanSTARRS telescope located in Hawaii. It is 9 million kilometers from Earth and measures 45-60 meters across.
This asteroid can only be observed from Earth in April each year for only a few weeks, and because of Kamoalev’s small size, the most powerful telescopes are needed to study it. Nature recently published an article by a team of American scientists from the University of Arizona who have been observing Kamoalev for several years with the Large Binocular Telescope located on Mount Graham in southern Arizona.
Initial measurements of Kamoalev’s reflectance spectrum in 2016 showed that rocks on the asteroid’s surface were chemically very similar to the lunar rocks that were delivered to Earth by Apollo expeditions. This has led astronomers to confusion: we still did not know about asteroids of lunar origin.
Scientists at the University of Arizona looked at known spectra of near-Earth asteroids and found no analogues of Kamoalev. For three years, astronomers argued about possible hypotheses for the asteroid’s origin. Observations in 2020 did not take place because of the COVID-19 pandemic. And only in April 2021 data were collected, which added weight to the “lunar” hypothesis of the formation of Kamoalev. It was possible to do this thanks to the clarification of its orbit.
Kamoalev’s orbit is close to the Earth’s, but has a slight tilt relative to the ecliptic plane. This is unusual for other near-Earth asteroids. It is extremely unlikely that an asteroid that accidentally comes close to Earth will fall into such an orbit. However, if it happens, its lifetime in such an orbit will not exceed 300 years. At the same time, observations show that Kamoaleva has been in its orbit for about 500 years. This does not prove, but indirectly supports the version that the asteroid was formed here – probably by breaking away from the Moon during a collision with another space body.