On September 29, 2024, Earth welcomed the arrival of a brief cosmic companion: a near-Earth asteroid dubbed 2024 PT5. This small celestial body is being referred to as Earth’s “mini-moon,” and it marks another fascinating chapter in the story of our planet’s interactions with space debris.
Initially detected on August 7, 2024, by researchers Carlos and Raúl de la Fuente Marcos at the Universidad Complutense de Madrid, 2024 PT5 measures roughly 33 feet wide—about the size of a standard school bus. According to the authors' findings documented in Research Notes of the AAS, this mini-moon is expected to accompany our planet for about 57 days before moving on to continue its orbit around the sun.
The phenomenon of mini-moons, which are typically asteroids caught temporarily by Earth's gravity, isn’t entirely new. Previous cosmic visitors have included the asteroid 2022 NX1, which was captured by Earth’s gravity back in 1981 and reappeared just last year, with another predicted return for 2051. Similarly, 1991 VG was close enough to Earth in February 1992 to spark interest, though it didn’t manage to complete its orbit.
Another noteworthy example includes asteroid 2006 RH120, which remained gravitationally bound to our planet for about one year, from July 2006 to July 2007. Then there's asteroid 2020 CD3, which orbited Earth for several years before venturing off again.
What makes 2024 PT5 particularly intriguing is its expected rapid departure. Having been drawn within 2.8 million miles of Earth, this small asteroid will not achieve complete orbit around our planet. Instead, it is set to escape Earth's gravitational embrace on November 25, 2024. This follows its brief stay within the Arjuna asteroid belt, located about 93 million miles from the sun, which hosts numerous asteroids often attracting scientific interest.
Due to its limited size—300,000 times smaller than our permanent moon—the visibility of this new mini-moon poses quite the challenge for stargazers. Despite some of its nearest neighboring objects coming within millions of miles, 2024 PT5 remains too faint and small for backyard telescopes or binoculars. According to Professor Carlos de la Fuente Marcos, only professional telescopes will be able to capture images of this fleeting companion. “The object is too small and dim for typical amateur telescopes and binoculars,” he stated, indicating the specialized equipment necessary for viewing it.
Interestingly, the asteroid is expected to make another close sweep by Earth come January 2025 and will pass again in 2055, providing future opportunities for observation. The recurring nature of these mini-moons serves as yet another reminder of the dynamic and ever-changing backdrop of our solar system and the abundant activity of near-Earth objects.
Though it might be hard to spot, the recent arrival of 2024 PT5 offers astronomers and space enthusiasts alike something to ponder: how often does Earth snag such visitors, and what does this say about our gravitational reach and the behavior of celestial bodies around us?
