Stargazers are in for an exciting celestial event this autumn as a small asteroid is poised to be temporarily captured by Earth’s gravity, creating a ‘mini-moon.’ From September 29 to November 25, this asteroid will orbit Earth before eventually breaking free.
Though the news has thrilled space enthusiasts, the mini-moon is a small, dim object that won’t be visible to the naked eye. Viewing it will require professional-grade telescopes, as even binoculars or home telescopes won’t suffice.
Dr. Jennifer Millard, host of the Awesome Astronomy podcast, shared with the BBC that telescopes will provide spectacular images of the asteroid. “You’ll be able to see stunning pictures of this tiny dot zipping past the stars,” Millard said.
The asteroid, known as 2024 PT5, comes from the Arjuna asteroid group, known for having orbits similar to Earth’s. It was first discovered on August 7 by NASA’s Asteroid Terrestrial-Impact Last Alert System (ATLAS) and is about 33 feet wide.
“It won’t complete a full orbit around Earth. The planet’s gravity will nudge its path before it continues its journey,” Millard explained.
Asteroids occasionally pass close to Earth, sometimes coming as near as 2.8 million miles (4.5 million kilometres). If an asteroid like 2024 PT5 is travelling at a relatively slow speed—around 2,200 mph (3,540 km/h)—Earth’s gravity can trap it temporarily, just like it’s expected to this weekend.
Mini-moons have been observed before, and it’s likely many more have passed unnoticed. Some, like asteroid 2022 NX1, even return for repeat appearances, becoming a mini-moon in both 1981 and 2022.
If you miss this event, don’t worry—2024 PT5 is predicted to return to Earth’s orbit in 2055.
“This story highlights how active our solar system is and how much there still is to discover. This asteroid was only detected earlier this year,” Millard added.