For nearly two months this year, Earth’s moon will have company — a second moon.
Technically, it isn't a second moon, but rather an asteroid from the Arjuna asteroid belt — named 2024 PT5 — that will be caught in the Earth's gravitational pull, according to a study in the journal Research Notes of the American Astronomical Society.
This is how many “mini-moons” are formed. An object in space can get caught in the Earth’s gravitational pull, make a full rotation around the planet and be classified as an orbiter — or be labeled a flyby if it doesn’t make a full rotation around the Earth, which is what 2024 PT5 is doing.
2024 PT5, discovered on Aug. 7, is following a horseshoe-shaped path, which means that it will make a semi-orbit of the Earth and then return to its normal sun-centered orbit. Researchers said the mini-moon will take place from Sept. 29 until Nov. 25.
Paul Chodas, director of the Center for Near Earth Object Studies at NASA's Jet Propulsion Laboratory, told the New York Times that based on the asteroid's motion there's a chance that it originated from Earth's actual moon.
While the average person may not see a second moon every day, this isn’t the only time the Earth’s moon has had a companion.
“Earth can regularly capture asteroids from the Near-Earth object (NEO) population and pull them into orbit, making them mini-moons,” the study said. In 1981 and 2022, researchers said, a flyby called 2022 NX1 was another short-lived mini-moon.
Unfortunately, it will be difficult to see 2024 PT5 in the night sky, as it isn’t big enough.
"The object is too small and dim for typical amateur telescopes and binoculars," Carlos de la Fuente Marcos, lead author of the AAS study, told Space.com. "However, the object is well within the brightness range of typical telescopes used by professional astronomers."