Rare ‘mini-moon’ to pass over Ontario this fall

This month, Earth will snag a second moon—well, not exactly. A tiny asteroid will temporarily join our orbit, giving us a rare, fleeting companion in the sky.

On Sept. 29 Earth will briefly gain a second moon as a small asteroid, 2024 PT5, gets caught in its gravitational pull, reports Space.com

Discovered in August (2024) by NASA’s Asteroid Terrestrial-impact Last Alert System, the 10-metre-wide asteroid will stick around until Nov. 25 before returning to its orbit around the Sun.

Astronomers say that 2024 PT5, part of the Arjuna asteroid belt, won’t be visible to the naked eye due to its size and distance. The asteroid is reportedly ten times farther from Earth than our moon and poses no risk of impact.

Earlier this month, a user on X (formerly Twitter) by the name Tony Dunn posted a simulation of asteroid 2024 PT5, showing it making a slow loop around Earth from August to December 2024. The yellow portion of its path indicates when it gets close enough to be considered a mini-moon or temporary satellite of Earth.

This is not the first time Earth has picked up a temporary satellite. Previous mini-moon events include 2020 CD3 and 2006 RH120, with captures lasting anywhere from weeks to months.

According to researchers from the Complutense University of Madrid, as cited by Space.com, although 2024 PT5 will stay near Earth for 57 days, it won’t complete a full orbit. However, it will make a close approach similar to other quasi-satellites.

Following its departure, the asteroid is expected to pass Earth once again in early January 2025, although it is unlikely to be recaptured during that flyby.

Newly-discovered #asteroid 2024 PT5 is about to undergo a “mini-moon event” when its geocentric energy becomes negative from September 29 – November 25.https://t.co/sAo1qSRu3J pic.twitter.com/pVYAmSbkCF

— Tony Dunn (@tony873004) September 10, 2024