The second moon is about to leave Earth

A mini-moon the size of a bus is orbiting Earth in its final days and won't reappear until 2055.

Asteroid 2024 PT5 has been orbiting Earth since September 29. It was first detected on August 7 by a NASA-funded asteroid warning system. The object is about 10 meters wide, but it is not a threat to Earth , according to Sun. 2024 PT5 is also much smaller than the Moon (about 3.4 million meters wide).

Simulation of a miniature moon orbiting the Earth along with the real moon. (Photo: Earth).

Mini-moons aren't particularly rare, but they can be tricky to spot. 2024 PT5 is particularly interesting because of its size. It's one of the largest mini-moons, according to Barbara Castanheira Endl, an assistant professor of physics at Baylor University in Texas. They're so faint that they can only be seen through the light they reflect.

2024 PT5 will leave Earth's orbit on November 25. It passed close to Earth as a mini-moon in the 1960s. Researchers predict it won't be seen again until 2055. They determined it came from the Arjuna asteroid belt, which orbits Earth for about a year.

Asteroid 2024 PT5 flew past Earth at a distance of nine times that of the Moon. Based on the similarity between the motion of 2024 PT5 and Earth, scientists at NASA's Center for Near-Earth Object Studies (CNEOS) suspect that it could be a large rock ejected from the surface of the Moon after a collision long ago.

2024 PT5 was discovered by the University of Hawaii's Asteroid Terrestrial-impact Last Alert (ATLAS) system in Sutherland, South Africa. The asteroid will continue to move away from Earth and continue its orbit around the Sun. If it gets close to Earth, it will burn up, according to Matt Pryal, assistant professor of astronomy at the University of Virginia. " 2024 PT5 helps us better understand near-Earth asteroids, how to detect them, and predict when they will come close ," Pryal said.