Near-earth asteroid could be a misplaced fragment of the moon

A near-Earth asteroid named Kamo`oalewa could possibly be a fraction of our moon, in response to a brand new paper printed in Nature Communications Earth and Environment by a staff of astronomers led by the University of Arizona.

Kamo`oalewa is a quasi-satellite—a subcategory of near-Earth asteroids that orbit the sun however stay comparatively near Earth. Little is understood about these objects as a result of they’re faint and troublesome to look at. Kamo`oalewa was found by the PanSTARRS telescope in Hawaii in 2016, and the identify—present in a Hawaiian creation chant—alludes to an offspring that travels by itself. The asteroid is roughly the scale of a Ferris wheel—between 150 and 190 toes in diameter—and will get as shut as about 9 million miles from Earth.

Due to its orbit, Kamo`oalewa can solely be noticed from Earth for a number of weeks each April. Its comparatively small size implies that it may solely be seen with one of many largest telescopes on Earth. Using the UArizona-managed Large Binocular Telescope on Mount Graham in southern Arizona, a staff of astronomers led by planetary sciences graduate scholar Ben Sharkey discovered that Kamo`oalewa’s sample of mirrored mild, referred to as a spectrum, matches lunar rocks from NASA’s Apollo missions, suggesting it originated from the moon.

The staff cannot but make certain the way it could have damaged unfastened. The motive, partly, is as a result of there aren’t any different recognized asteroids with lunar origins.

“I looked through every near-Earth asteroid spectrum we had access to, and nothing matched,” mentioned Sharkey, the paper’s lead writer.

The debate over Kamo`oalewa’s origins between Sharkey and his adviser, UArizona affiliate professor Vishnu Reddy, led to a different three years of looking for a believable clarification.

“We doubted ourselves to death,” mentioned Reddy, a co-author who began the undertaking in 2016. After lacking the prospect to look at it in April 2020 on account of a COVID-19 shutdown of the telescope, the staff discovered the ultimate piece of the puzzle in 2021.

“This spring, we got much needed follow-up observations and went, ‘Wow it is real,'” Sharkey mentioned. “It’s easier to explain with the moon than other ideas.”

Kamo`oalewa’s orbit is one other clue to its lunar origins. Its orbit is much like the Earth’s, however with the slightest tilt. Its orbit can be not typical of near-Earth asteroids, in response to research co-author Renu Malhotra, a UArizona planetary sciences professor who led the orbit evaluation portion of the research.

“It is very unlikely that a garden-variety near-Earth asteroid would spontaneously move into a quasi-satellite orbit like Kamo`oalewa’s,” she mentioned. “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 mentioned. Her lab is engaged on a paper to additional examine the asteroid’s origins.

Kamo`oalewa is about 4 million instances fainter than the faintest star the human eye can see in a darkish sky.

“These challenging observations were enabled by the immense light gathering power, of the twin 8.4-meter telescopes of the Large Binocular Telescope,” mentioned research co-author Al Conrad, a employees scientist with the telescope.

The research additionally included information from the Lowell Discovery Telescope in Flagstaff, Arizona. Other co-authors on the paper embrace Olga Kuhn, Christian Veillet, Barry Rothberg and David Thompson from the Large Binocular Telescope; Audrey Thirouin from Lowell Observatory and Juan Sanchez from the Planetary Science Institute in Tucson.