Syracuse, N.Y. (NCC News) — On Sunday, Earth captured a temporary new moon!
According to the Asteroid Terrestrial-Impact Last Alert System, or ATLAS for short, a program funded by NASA, a 10 meter wide asteroid entered Earth’s orbit on Sunday, Sept. 29 and will stick around until Monday, Nov. 25. The ATLAS system first spotted the asteroid on Wednesday, Aug. 7.
PT5, a small asteroid that is considered a “mini-moon,” is part of a small asteroid belt, called the Arjuna asteroid belt, that typically orbits around the sun. The asteroid will take a horseshoe shaped orbit around the Earth.
“Mini-moons” range from small asteroids to literal space garbage that enter into Earth’s gravitational pull and hang out long enough to complete a limited rotation around the Earth.
Don’t get too excited over this “mini-moon.” Unlike Earth’s regular moon, which has been in capture for around 4 billion years, PT5 will not be visible to the naked eye. The human eye typically sees objects at a 6 magnitude or below, but PT5 has a magnitude of roughly 27.6.
For some perspective, Earth’s moon is a -13 magnitude, making it easily distinguishable to the naked eye.
It won’t even be noticeable with recreational telescopes or binoculars that can find objects up to a 16 to 17 magnitude threshold. It will be discernable by use of professional telescopes.
The PT5 capture will last longer than a usual asteroid capture that Earth exhibits multiple times per decade. Those events only last about a week and are known as “short-captures.”
PT5 is the first major visitor that Earth has had since 2022 when Asteroid 2022 YG entered Earth’s gravitational pull. Also that same year, Earth experienced the return of a guest that stopped by in 1981, the Asteroid NX-1.
While this is an extraordinary phenomenon, it’s not uncommon for Earth to sway an object into its gravitational pull from time to time.
PT5 will partially orbit the Earth for 57 days before making its exit and returning to its typical path with the Arjuna belt. It is expected to return in 2055.