Near-Earth asteroid may actually be a miniature moon

New research led by a team of astronomers from the University of Arizona has found that the near-Earth asteroid named Kamo’oalewa, a quasi-satellite that orbits the Sun but remains relatively close to Earth, could be a fragment of our moon.

With a diameter between 150 and 190 feet, this asteroid is roughly the side of a Ferris wheel and gets as close as about nine million miles from Earth. It has been discovered by the PanSTARRS telescope in Hawaii in 2016 and got its name from a Hawaiian creation chant, alluding to a child travelling on its own. 

Due to its orbit, Kamo’oalewa can only be seen from Earth for a few weeks each April. Moreover, since it is about four million times fainter than the faintest star the human eye can see in a dark sky, this asteroid can only be observed with the help of very powerful telescopes.

By using the Large Binocular Telescope on Mount Graham in southern Arizona, researchers found that the asteroid’s spectrum or pattern of reflected light matched lunar rocks from NASA’s Apollo space missions. If this is the case, Kamo’oalewa would be the first known asteroid with lunar origins.

“I looked through every near-Earth asteroid spectrum we had access to, and nothing matched,” said study lead author Benjamin Sharkey, an astronomer from the University of Arizon. “This spring, we got much needed follow-up observations and went, ‘Wow it is real.’ It’s easier to explain with the moon than other ideas.”

Another clue that the asteroid might be a part of the moon is its peculiar orbit, which is not typical of near-Earth asteroids and is more similar to the Earth’s orbit. 

“It is very unlikely that a garden-variety near-Earth asteroid would spontaneously move into a quasi-satellite orbit like Kamo`oalewa’s,” said study co-author Renu Malhotra, a professor of Planetary Sciences at the University of Arizona. “It will not remain in this particular orbit for very long, only about 300 years in the future, and we estimate that it arrived in this orbit about 500 years ago.”

The study is published in the journal Nature Communications: Earth & Environment.

—

By Andrei Ionescu, Earth.com Staff Writer