2023-10-26 19:45:51
Kamooalewa (Kamo`oalewa) was discovered by the PanSTARRS telescope from Hawaii in 2016. The asteroid has a diameter of less than a hundred meters and is approaching within about 14 million kilometers of Earth. Kamooalewa’s orbit is similar to that of Earth, but with a slight inclination. Kamooalewa is a quasi-satellite, a subcategory of near-Earth asteroids that, although they orbit the Sun, remain relatively close to Earth during their journey. Little is known about these objects because they are small and therefore difficult to observe. Kamooalewa’s brightness is about 4 million times less than that of the brightest star the human eye can see in a dark sky.
In 2021, a team of astronomers from the University of Arizona in the United States suggested that Kamooalewa could be a piece of the Moon. Several clues pointed to this; For example, Kamooalewa’s spectrum is different from that of other asteroids that pass close to Earth, and is in good agreement with that of the Moon. The hypothesis put forward was that Kamooalewa could have been ejected from the lunar surface as a result of the impact of a large meteorite.
Now, two years later, another team of scientists from the same university has determined how Kamooalewa ended up becoming an asteroid and then a quasi-satellite.
In the new study, the team, including, among others, Jose Daniel Castro-Cisneros and Renu Malhotra, sought to determine how feasible it could be for a piece of the Moon detached from it to adopt a special orbit that would allow it to be a quasi-satellite. Such an orbit change is a highly unlikely phenomenon. Lunar fragments that have enough kinetic energy to escape the Earth-Moon system also have too much energy to adopt the orbital pattern that defines a quasi-satellite.
Thanks to numerical simulations that precisely take into account the gravitational forces of all the planets in the solar system, the authors of the new study have discovered that some lunar fragments were able to adopt orbits typical of quasi-satellites.
Kamooalewa could be one of those fragments torn from the Moon during an impact on it some day in the last million years.
The Earth seen from the Moon. (Photo: NASA)
Throughout its history, the Moon has been bombarded by meteorites, including asteroids or fragments of these, which is evident in the numerous impact craters that remain on its surface. Impact craters are created when such cosmic objects collide with the surface of a planet or satellite. In the case of the Moon, these impacts can cause lunar material to be ejected from the Moon’s surface, although most of that material usually falls back to the Moon.
Some of the ejected matter falls to the Earth, and that is how we get meteorites from the Moon. But a small fraction could escape the gravity of both the Moon and Earth and end up orbiting the Sun like other asteroids that pass close to Earth. The numerical simulation suggests that Kamooalewa may be one of the smallest fragments that managed to enter the orbit that the Earth follows around the Sun.
Until now, only asteroids from beyond the orbit of Mars have been considered a source of bodies capable of passing close to Earth. With the latest findings about Kamooalewa, it is worth seriously considering whether the Moon is the most likely source of quasi-satellites like this. If this is so, then there are surely many pieces of the Moon waiting to be discovered among the most sought-after asteroids. they approach the Earth.
The study is titled “Lunar ejecta origin of near-Earth asteroid Kamo’oalewa is compatible with rare orbital pathways.” And it has been published in the academic journal Communications Earth & Environment. (Source: NCYT from Amazings)
#piece #Moon #asteroid #quasisatellite