Near Earth Asteroid Could Be Lost Piece of Moon

A near-Earth asteroid called Kamo’oalewa could be a fragment of our moon, according to an article published in Communications Earth and Environment by a team of astronomers led by the University of Arizona.

Kamo’oalewa is a quasi-satellite – a subcategory of near-Earth asteroids that orbit the Sun but remain relatively close to Earth. Little is known about these objects because they are weak and difficult to observe. Kamo’oalewa was discovered by the PanSTARRS telescope in Hawaii in 2016, and the name – found in a corner of Hawaiian creation – alludes to offspring traveling on their own. The asteroid is about the size of a Ferris wheel and reaches about 14 million kilometers from Earth.

Due to its orbit, Kamo’oalewa can only be observed from Earth for a few weeks each April. Its relatively small size means it can only be seen with one of the largest telescopes on Earth. Using the Large Binocular Telescope managed by Arizona at Mount Graham, southern Arizona, a team of astronomers led by Arizona graduate student in planetary sciences Ben Sharkey found that Kamo’oalewa’s reflected light pattern, called the spectrum, matches to moon rocks from NASA’s Apollo missions, suggesting that it originated from the moon.

Researchers are still unsure how the asteroid could have broken free of the moon. In part, this is because there are no other known asteroids of lunar origin.

“I looked through every spectrum of near-Earth asteroids that we had access to, and nothing matched,” said Sharkey, the lead author of the article.

A debate over the origins of Kamo’oalewa between Sharkey and his adviser, Arizona Associate Professor of Lunar and Planetary Sciences, Vishnu Reddy, led to another three years of searching for a plausible explanation.

“We doubt ourselves to death,” said Reddy, a co-author who started the project in 2016. After missing the chance to observe the asteroid in April 2020 due to a shutdown of COVID-19 from the Large Binocular Telescope , the team discovered the final piece of the puzzle in 2021.

“This spring, we received much-needed follow-up observations and we were surprised, ‘Wow, it’s real,’” said Sharkey. “It’s easier to explain with the moon than with other ideas.”

Kamo’oalewa’s orbit is another clue to its lunar origins. Its orbit is similar to Earth’s, but with the slightest inclination. Its orbit is also not typical of near-Earth asteroids, according to study co-author Renu Malhotra, a professor of planetary sciences at Urizona who led the orbit analysis portion of the study.

“It’s very unlikely that a near-Earth asteroid, a garden variety, would spontaneously move into a near-satellite orbit like Kamo’oalewa,” said Malhotra, whose lab is working on a paper to further investigate the origins. of the asteroid. “It won’t stay in this specific orbit for very long, only about 300 years into the future, and we estimate that it arrived in this orbit about 500 years ago.”

Kamo’oalewa is about 4 million times fainter than the faintest star the human eye can see in a dark sky.

“These challenging observations were made possible by the immense light-gathering power of the twin 8.4-meter telescopes of the Large Binocular Telescope,” said study co-author Al Conrad, a scientist on the telescope’s team.

The study also included data from the Lowell Discovery Telescope in Flagstaff, Arizona. Other co-authors on the article include Olga Kuhn, Christian Veillet, Barry Rothberg and David Thompson of the Large Binocular Telescope; Audrey Thirouin of the Lowell Observatory; and Juan Sanchez of the Planetary Science Institute in Tucson. The research was funded by NASA’s Near-Earth Object Observation Program.