What about the mysterious asteroid Kamo’oalewa, which orbits the sun in an orbit similar to that of the earth? Analyzes of its reflected light spectrum now show that the celestial body is made of material that is similar to that of the moon. It is possible that Kamo’oalewa was created from fragments of a former asteroid impact on our satellite, say the scientists.
The earth-moon system moves through space in a neighborhood of many smaller celestial bodies: In our solar system there is an illustrious society of so-called near-earth asteroids. Some of them are traveling on special orbits: They orbit the sun in a similar way to the earth. They are therefore called quasi-satellites. Little is known about these near-earth objects, as they are only very weakly illuminated and therefore difficult to observe.
In 2016, astronomers added the asteroid Kamo’oalewa to the well-known quasi-satellite: the PanSTARRS telescope in Hawaii was able to capture its fine glow, which is about four million times weaker than that of the faintest stars that the human eye can see in the night sky. According to the data, Kamo’oalewa has a diameter of up to about 100 meters. It orbits the sun in an orbit that differs only slightly from the earth and also takes about a year for one orbit. With the current constellation, it always comes closest to Earth in April. The closest approximation is around 15 million kilometers.
Interesting patterns in the faint shimmer
In order to find out more about Kamo’oalewa, the researchers working with Benjamin Sharkey from the University of Arizona in Tucson took a closer look at him. The Large Binocular Telescope and the Lowell Discovery Telescope, which are located in Arizona, were used. Their high sensitivity to light enabled spectral analyzes of the weak light that is reflected from the small celestial body. Based on the pattern of the wavelengths, it was possible to draw conclusions about certain material properties as well as comparisons with the signatures of the light spectrum of other celestial bodies, the scientists explain.
As they report, it emerged from the analyzes that the composition of Kamo’oalewa is characterized by silicate material. A slight shift to the reddish spectrum distinguishes Kamo’oalewa from the signatures known from other asteroids in the inner solar system, say the scientists. “I’ve looked through every near-earth asteroid spectrum we had access to and none of them matched the results,” says Sharkey. Further comparisons then showed, however, that the patterns of the reflected light from Kamo’oalewa agree with those of lunar rocks, the characteristics of which are known from samples from NASA’s Apollo missions.
Debris body of the moon?
As the researchers explain, this finding now sheds light on the possible origin of this asteroid with its particularly Earth-like orbit. “The reflection spectrum of Kamo’oalewa supports the explanation that it was formed from debris from the moon,” the scientists write. Specifically, an asteroid could once have hit the moon, throwing material far out, from which Kamoʻoalewa then formed.
Investigations of the orbit of Kamo’oalewa as part of the study also support the origin of the asteroid in the Earth-Moon system. It differs from that of the earth only by a slight inclination and is in a special orphan atypical for near-earth asteroids. “It is very unlikely that an ordinary near-Earth asteroid would spontaneously swing into a quasi-satellite orbit like that of Kamo’oalewa,” explains co-author Renu Malhotra of the University of Arizona.
However, some questions about the interesting celestial body still remain open. That’s why astronomers want to keep an eye on him.
Source: University of Arizona, Articles: Communications Earth & Environment, doi: 10.1038 / s43247-021-00303-7