Planetary science: Earth’s quasi-satellite Kamo’oalewa could be made of Moon material

One of Earth’s quasi-satellites, known as Kamo’oalewa, could be comprised of lunar-like material and may have been formed by an ancient impact on the Moon, according to an article published in Communications Earth & Environment.

Quasi-satellites are small objects that remain close to the Earth whilst they orbit the sun. Despite being close to Earth, they are difficult to observe and so little is known about their origin or composition.

Benjamin Sharkey and colleagues examined the light reflected from Kamo’oalewa using the Large Binocular Telescope and the Lowell Discovery Telescope. The authors found that it had a red reflectance spectrum, very similar to that of minerals on the Moon’s surface. This finding, coupled with an assessment of Kamo’oalewa’s orbital path, suggests that it most likely originated as a part of the Earth-Moon system, perhaps as debris from an impact event or from the gravitational break-up of a larger body during a close encounter with the Earth and Moon. The findings offer rare insights into the formation of Earth’s quasi-satellite population.