Earth’s Former Mini-Moon Set to Revisit in 27 Years

Earth has temporarily acquired a second moon, an asteroid named 2024 PT5, which was captured by our planet’s gravitational pull on Sunday, September 29. This isn’t the first instance of Earth snagging a “mini-moon.”

The asteroid was initially spotted on August 7 by the Asteroid Terrestrial-Impact Last Alert System (ATLAS). It was Carlos and Raúl de la Fuente Marcos, researchers at Universidad Complutense de Madrid, who first observed the asteroid and documented their discovery in the Research Notes of the AAS.

Like other asteroids, 2024 PT5 orbits the sun, but occasionally, these space rocks come close enough to Earth that they are temporarily drawn in by its gravity. This phenomenon, while rare, has occurred before.

Historically, Earth has captured other mini-moons. For instance, a cosmic body named 2022 NX1 was caught by Earth’s gravity in 1981 and reappeared in 2022, staying briefly each time before returning to space; it is expected back in 2051. Another temporary mini-moon, 1991 VG, came close to Earth in February 1992 but did not complete an orbit.

More notably, the asteroid 2006 RH120 was gravitationally bound to Earth for about a year, from July 2006 to July 2007. Similarly, asteroid 2020 CD3 orbited Earth for several years before departing in May 2020.

The current mini-moon, 2024 PT5, shares characteristics with 2022 NX1, in that it won’t complete a full orbit around Earth and will depart on November 25. It resides in the Arjuna asteroid belt, where space rocks follow orbits similar to Earth’s, around 93 million miles from the sun.

Despite the close proximity of some Arjuna belt objects, which can come within about 2.8 million miles of Earth, 2024 PT5 is too small and faint to be seen with amateur telescopes or binoculars. In comparison to our moon, which is 2,159 miles in diameter, 2024 PT5 is only about 37 feet across.