As Earth says goodbye to 'mini-moon,' asteroid's possible lunar origin revealed
Earth is bidding farewell to a tiny asteroid that joined its orbit for nearly two months.
The asteroid, known as 2024 PT5, is set to be drawn away from Earth by the powerful pull of the sun on Monday. Called a "mini-moon" of sorts by some, it temporarily entered Earth's orbit on Sept. 29 from the Arjuna asteroid belt, which follows a similar orbital path around the sun as the Earth.
Now, as the asteroid is set to depart from view, evidence is suggesting it was visiting its cosmic parents.
"Current research favors its rapid rotation with a rotational period under one hour, to be expected if 2024 PT5 is either a large boulder from the surface of the moon or a fragment from a larger object," Universidad Complutense de Madrid professor Carlos de la Fuente Marcos told Space.com.
He said the leading theory suggests the asteroid was ejected from the moon's surface after one of the many collisions that has left the moon's surface with its iconic craters.
"This object has helped the community to realize that lunar ejecta is probably a main source for the material that constitutes the Arjuna asteroid belt," Marcos told the outlet.
What is a 'mini-moon'?
"Mini-moon" events occur when asteroids or floating pieces of space junk temporarily orbit the Earth. Their length of time in orbit varies, with some completing a full rotation around the Earth, while others peel away after a few months, weeks or even days.
In order to be considered a "mini-moon," an incoming object must reach Earth at a range around 2.8 million miles and at a steady space of about 2,200 mph, according to Marcos. He told Space.com the asteroid met those conditions in late September.
NASA said 2024 PT5 does not qualify as a "mini-moon" because it was never captured by Earth's gravity and remained more of a "distant companion of our planet" rather than a satellite. "So while it’s not quite a 'mini-moon,' 2024 PT5 is an interesting object and NASA has plans to track it with planetary radar," NASA said.
How big is the asteroid?
2024 PT5 is only 33 feet wide, making it too small to see from Earth without a high-powered telescope.
"The object is too small and dim for typical amateur telescopes and binoculars. However, the object is well within the brightness range of typical telescopes used by professional astronomers," Marcos told Space.com.
When will the asteroid come back?
"It will not follow a full orbit around Earth," Marcos said. After 2024 PT5 is pulled away from Earth on Monday, the asteroid will make its next approach on Jan. 9, he said.
NASA said it will track 2024 PT5 during the its next close pass of Earth with the Goldstone Solar System Radar, which is positioned near the California city of Barstow.
Contributing: Max Hauptman and Anthony Robledo, Paste BN
(This story was updated to add new information and because an earlier version included an inaccuracy.)