An asteroid like this isn’t normal.
It’s likely that a space rock that appears to follow Earth around the sun (because it has a very similar orbit) is a chunk of the moon. The 150 to 190-foot-wide asteroid poses no threat to Earth, but it’s certainly a curiosity in our solar system’s neighborhood.
Experts found that the asteroid (Kamo’oalewa) reflected sunlight significantly differently from typical asteroids in the research published by the science journal Communications Earth and Environment. Instead, it reflected light more akin to lunar rocks.
In fact, the moon’s origins seemed unlikely. In a statement, Vishnu Reddy, an associate professor of lunar and planetary sciences at the University of Arizona and co-author of the reserch, said, “We doubted ourselves to death.”
Following several years of observations with powerful telescopes, and new observations in 2021, the moon became the most likely explanation. According to Ben Sharkey, a University of Arizona graduate student studying planetary science and study co-author, “it’s easier to explain with the moon.”
Astronomers observed Kamo’oalewa in 2016 and produced a visualization of its orbit, which you can see below. The asteroid orbits the sun each year, which is why it’s been called “Earth’s constant companion.” Fortunately, this constant companion never gets closer than 9 million miles from Earth. It’s about 38 times farther than the moon.
Near-Earth objects of Kamo’oalewa’s size could potentially pose a threat to the Earth. About 50,000 years ago, an asteroid measuring 100 to 170 feet across left a 600-foot-deep crater in Arizona. A similar-size impact today would destroy a city the equivalent of Kansas City, David Kring, an impact specialist at the Lunar and Planetary Institute, told NASA in 2021.
In the next couple of weeks, NASA will launch a mission to another asteroid, called Dimorphos, in order to test humanity’s ability to deflect an asteroid destined to strike Earth. However, NASA has never issued a warning for an imminent asteroid strike.