Astronomers used the Large Binocular Telescope in southern Arizona to show that the asteroid Kamo'oalewa, seen in an artist's impression, may be a lost fragment of the moon. Image by Addy Graham/University of Arizona
Nov. 11 (UPI) -- A near-Earth asteroid named Kamo'oalewa, which orbits the sun but remains close to the Earth, may be a moon fragment, University of Arizona researchers said in a study published Thursday in the journal Nature Communications Earth and Environment.
Researchers found that the asteroid's patter of reflected light, called a spectrum, matched lunar rocks from NASA's Apollo missions, indicating it broke off from the moon.
They initially doubted themselves because no other known asteroids have lunar origins, but after three years of looking for another plausible explanation, they found it was the most likely scenario, according to the study.
"We doubted ourselves to death," study co-author Vishnu Reddy, a university professor who started the project in 2016, said in a press release.
Study lead Ben Sharkey, a planetary sciences graduate student at Arizona, said that the team reached its finding this spring after their observations were delayed by the shutdown of the telescope last year due to the COVID-19 pandemic.
"We got much needed follow-up observations and went, 'Wow it is real,'" Sharkey said. "It's easier to explain with the moon than other ideas."
Study co-author, Renu Malhotra, a university professor who led the orbit analysis portion of the study, said Kamo'oalewa's orbit, which was similar to the Earth's, but with the slightest tilt, was not typical of near-Earth Asteroids, and was another clue to its lunar origins.
"It is very unlikely that a garden-variety near-Earth asteroid would spontaneously move into a quasi-satellite orbit like Kamo'oalewa's," Malhotra said in the release.
"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," Malhotra said.
Researchers defined Kamo'oalewa as one of the Earth's "quasi-satellites," which "are faint and difficult to observe."
The research team used the Large Binocular Telescope on Mount Graham in southern Arizona for the study, which also included data from the Lowell Discovery Telescope in Flagstaff, Ariz.
The near-Earth asteroid, which is roughly the size of a Ferris wheel and gets as close as 9 million miles from the Earth, was discovered in 2016 by the Panoramic Survey Telescope and Rapid Response System located at Haleakala Observatory in Hawaii.
The name Kamo'oalewa, found in a Hawaiian creation chant, alludes to an offspring that travels on its own.
Back in 2018, a study found that both the Earth and moon formed from the same giant collision.
The scientists in that study hypothesized that a pair of planet-size bodies collided to create a donut-shaped cloud of vaporized rock called a synestia.
As the rock vapors condensed into liquid form, the cloud shrunk and transformed into molten planet, but a glob of vaporized rock escaped during impact, resulting in the seed for what became the Earth's moon.