Earth will gain a “mini-moon” in just a few days, when an asteroid the size of two SUVs will pay our planet a temporary visit, and leave right around Thanksgiving.
Asteroid 2024 PT5 will become a bonus moon around Earth on September 29. Ordinarily, this Near-Earth object (NEO) orbits the Sun on a path slightly wider than Earth’s. But the asteroid is moving at a low-enough velocity, and at close-enough range to our planet, that it will enter a horseshoe path around Earth.
“Earth can regularly capture asteroids from the Near-Earth object (NEO) population and pull them into orbit, making them mini-moons,” according to the team behind a paper published recently in Research Notes of the American Astronomical Society.
The upcoming mini-moon 2024 PT5 is a “temporarily captured flyby,” meaning it will not complete a revolution around Earth. It will depart on November 25 and not return for another three decades. Sometimes, however, objects do complete an orbit or more. One such instance happened from July 2006 to July 2007, when 2006 RH120 remained gravitationally-bound to our planet.
One of the four observatories that make up part of the NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS) discovered the 33-foot-long asteroid on August 7, the paper said. The asteroid appeared to the ATLAS Sutherland station in South Africa. The University of Hawaiʻi Institute for Astronomy operates ATLAS for NASA’s Planetary Defense Coordination Office. According to the space agency, in 2022 ATLAS became the first survey capable of searching for NEOs in the entire dark sky every 24 hours.
Scientists don’t think 2024 PT5 is an artificial object, such as a piece of debris from a rocket. Its dynamics look extremely similar to another confirmed natural object turned mini-moon, called 2022 NX1, that visited in 1981 and 2022, and which may return as a mini-moon in 2051.
Mini-moon phase excluded, 2024 PT5 travels around the Sun as an Apollo asteroid. These objects have semi-major axes larger than Earth’s axis. After the temporarily-captured flyby, which lasts about 57 days, it will depart Earth’s vicinity. It won’t return until 2055.
