For two months this fall, Earth will have not one but two moons. A rare celestial event will see asteroid 2024 PT5 temporarily orbiting our planet from September 29 to November 25, becoming Earth’s “mini moon.” Discovered on August 7 by NASA’s Asteroid Terrestrial-impact Last Alert System (ATLAS), this tiny space rock, measuring just 33 feet in length, will make its brief but exciting appearance in Earth’s orbit. Though small, its presence opens up fascinating opportunities for astronomers and space enthusiasts to study and explore.
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In a rare celestial event, asteroid 2024 PT5 will become Earth’s temporary mini moon. This space rock was discovered on August 7 by the NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS). It is only 33 feet long and is set to briefly orbit Earth from September 29 to November 25. After that, it will continue its journey through space.
Federica Spoto, an asteroid dynamics researcher at the Center for Astrophysics, Harvard & Smithsonian, stated, “It is pretty cool.” Though not involved with the study, she emphasized that studying 2024 PT5 will help scientists understand more about asteroids that approach Earth.
These temporary satellites, called “mini moons,” are hard to spot. They are small and move quickly. Often, they are mistaken for human-made space debris, such as parts of old rockets. However, astronomers believe 2024 PT5 is a natural object. Raúl de la Fuente Marcos, an astronomer at Complutense University of Madrid, said, “Every time an object with an orbit so Earth-like is discovered, there is a chance that we are just recovering space debris.” But with 2024 PT5, he added, “It is a natural object, no doubt about that.”
Adding to the intrigue, scientists think this asteroid may be a fragment of the moon. Paul Chodas, director of the Center for Near Earth Object Studies at NASA’s Jet Propulsion Laboratory, suggested it might have been ejected from the moon by a past impact.
There is some debate about whether 2024 PT5 truly qualifies as a mini moon. Typically, a mini moon must complete at least one full orbit around Earth. However, 2024 PT5 will follow a horseshoe-shaped path and won’t finish a complete revolution. Lance Benner, principal investigator of the asteroid radar research program at NASA’s Jet Propulsion Laboratory, said, “It certainly won’t complete one full revolution in the Earth-moon system this fall, so I’m not sure I would classify it as a mini moon.”
Beyond the excitement of having a temporary space companion, asteroids like 2024 PT5 offer future opportunities. Some contain valuable metals, leading to dreams of asteroid mining. Dr. Spoto added, “Every time they’re talking about asteroid mining, they talk about mini moons.” Future missions could potentially redirect metal-rich asteroids into orbit for mining purposes.
Astronomers also want to study objects like 2024 PT5 for planetary defense. The most significant threat comes from large near-Earth objects that could destroy cities. Though there are millions of smaller asteroids capable of causing widespread damage, many remain unidentified. As 2024 PT5 makes its close approach, it reminds us of the “busy highway” of space rocks around Earth. Understanding these objects is crucial, Spoto noted, as it is important for the safety of everyone on the planet.
