A New Mini-Moon to Arrive in Earth’s Orbit Later This Month

Step aside, Moon—Earth is about to gain a new natural satellite. This “mini-moon” will stay with us for the next two months, though it’s not its first visit, and it won’t be the last.

This temporary mini-moon is actually a small asteroid, about 10 meters (33 feet) wide, officially named 2024 PT₅. Discovered just last month, calculations show it will enter Earth’s orbit on September 29.

A Brief Visit

The asteroid will stay with us for 56.6 days, completing one orbit around Earth in that time. On November 25, it will escape Earth’s gravitational pull and continue its journey around the Sun. It will pass by Earth again on January 9, 2025, coming within 1.8 million kilometers (1.1 million miles), before heading back into space.

However, this won’t be its last visit. 2024 PT₅ is expected to return on November 8, 2055, though it will pass at a greater distance of 5.2 million kilometers (3.3 million miles).

The asteroid was first detected on August 7 by the Asteroid Terrestrial-impact Last Alert System (ATLAS), just a day before it made its closest approach to Earth at 567,000 kilometers (352,300 miles), about one and a half times the Moon’s distance.

A Temporary Mini-Moon

Astronomers from the Complutense University of Madrid, using data from JPL’s Small-Body Database and 122 observations over 21 days, calculated its orbit. They found that 2024 PT₅ follows a slow, horseshoe-shaped trajectory, leading to this brief “mini-moon” phase with Earth.

The asteroid’s orbital characteristics also gave the team clues about its origin. 2024 PT₅ appears to be part of the Arjuna group of near-Earth objects, which follow a similar distance, shape, and angle around the Sun as Earth. This makes it unlikely to be artificial space debris, unlike other objects previously detected by ATLAS.

This isn’t 2024 PT₅’s first encounter with Earth. Astronomers traced its path back 60 years and projected its future for the next 30 years, though interactions with the Earth-Moon system make further predictions less certain.

Before this year’s approach, the asteroid made close flybys in February 2003, April 1982, and March 1960, but all at a distance of over 8.2 million kilometers (5.1 million miles). The last time it came within a million kilometers was likely in October 1937, though the data becomes less reliable the further back it goes.

Future Encounters with 2024 PT₅

Looking ahead, the next confirmed visit will be in November 2055, with another possible close approach in January 2084 at a distance of 1.66 million kilometers (1 million miles).

Earth has had brief encounters with mini-moons before. In 2020, astronomers discovered a small rock, about 3.5 meters (11.5 feet) wide, that had been orbiting Earth for three years before drifting away shortly after its discovery.

In 2016, astronomers discovered a different type of mini-moon known as a “quasi-satellite.” Although it technically orbited the Sun, it was caught in Earth’s gravitational pull and followed closely behind. It was estimated to have been trailing Earth for nearly a century and is expected to continue doing so for several more years.

Read the original article on: Science Alert

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