A space traveler joined Earth’s orbit on Sept. 29 in the form of a small asteroid named 2024 PT5 and is set to depart on Nov. 25.
Dubbed the “mini-moon,” this asteroid is a rocky near-Earth object about 10 meters wide, discovered by ATLAS, a NASA-funded warning system known as the Asteroid Terrestrial-impact Last Alert System. One of its telescopes in Sutherland, South Africa, first spotted the bus-sized asteroid on Aug. 7, 2024.
Dr. Jim Buchholz, professor of mathematics and physics and astrophysicist, explained where the mini-moon originated.
“It is actually from Arjunas [asteroid belt]—it’s a very minor belt,” Buchholz said. The belt is considered minor because it is a secondary asteroid belt with a number of potential nearby asteroids.
When one of the asteroids breaks away from the belt and roams the solar system, it can be pulled into orbit—just like the mini-moon, 2024 PT5.
“We have what is called nearby asteroids that intersect our orbit. The asteroid belt […] doesn’t intersect our orbit,” Buchholz said.
Monitoring these nearby asteroids is essential to ensure their paths push them back out into the solar system rather than flinging them inward. If an asteroid were to spiral inward, it would crash somewhere on Earth, “[…] like a huge bomb going off,” Buchholz said.
Although the mini-moon has gained attention since its discovery, Buchholz noted, “This isn’t the first time that we’ve actually discovered and taken pictures of a [mini-moon] for a short period of time.” From 2006 to 2007, another “moon” smaller than 2024 PT5 entered Earth’s orbit and remained there for about 18 months.
While an asteroid the size of a bus may seem large, it is small compared to Earth’s actual moon. NASA reports that the object’s absolute magnitude, or brightness, is 27.489, making it invisible to the naked eye.
However, Buchholz explained that proper telescopes can snap photos of the mini-moon, though the result may be underwhelming.
“We have telescopes in Poland, Canada, both coasts in the United States, and down in Chile—we have them all over,” Buchholz said. These are all reflecting telescopes, which use mirrors instead of lenses.
Although many students were unaware of the mini-moon, CBU’s astronomy courses keep students informed.
Stephanie Duttera, a sophomore and former student of Dr. Buchholz, shared her experience taking a physics course as a business administration major. “[Astronomy] classes are largely shaped by the current astronomical climate and enhance students’ understanding of ongoing developments in space,” Duttera said.
For those interested in tracking the mini-moon without professional equipment, Buchholz offered advice.
“I would not trust social media,” Buchholz said. “With Photoshop, people are just faking stuff.”
Instead, he recommended reliable websites like nasa.gov and space.com for accurate information.
The asteroid will visit Earth’s vicinity for about two months before leaving for its next adventure in the solar system. NASA reports that 2024 PT5 could pass close to Earth again in January 2025.
For students interested in learning more about objects in the sky, Buchholz teaches an astrophotography course, where students can use telescopes to track and photograph such objects, much like the mini-moon.
