Earth to get ‘mini-moon’ 2024 PT5, orbiting for 2 months | All you need to know

Earth is set to witness a ‘mini-moon’ called 2024 PT5, a small asteroid that will not collide with Earth but will orbit around it, similar to the Moon, for a brief period of around two months by the end of this month.

According to a paper published in the Research Notes of the American Astronomical Society, the asteroid will be temporarily captured by Earth's gravity until around November. Detected by the Asteroid Terrestrial-Impact Last Alert System (ATLAS) on August 7, it will orbit Earth from September 29 to November 25 before breaking free from the planet's gravitational pull.

Astronomers refer to it as a “temporarily captured flyby” since it won’t complete a full orbit. In contrast, mini-moons that do complete a full orbit are known as “temporarily captured orbiters”.

A report by Live Science mentioned a study suggesting that 2024 PT5 likely originated from the Arjuna asteroid belt, which contains space rocks that orbit the sun near Earth. Due to its orbit being similar to Earth's, calculations show that the asteroid will return to orbit Earth in January 2025 and again in 2055.

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Is it normal for Earth to attract asteroids like this?

The research paper explained that Earth can periodically capture asteroids from the Near-Earth Object (NEO) population, pulling them into orbit and turning them into ‘mini-moons’. The researchers noted that the recently discovered Apollo-class NEO 2024 PT5 follows a path similar to that of 2022 NX1 and may soon become a mini-moon.

NASA considers any space object within about 120 million miles (190 million kilometres) of Earth as a “near-Earth object” and classifies larger objects within 4.7 million miles (7.5 million kilometres) as “potentially hazardous”.

NASA monitors around 28,000 asteroids through ATLAS, a system of four telescopes that scans the entire night sky every 24 hours.

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Previous instances of Earth getting ‘mini-moons’

- In 2020, a mini-moon was discovered, later identified as random space junk – a rocket booster from the 1966 Surveyor 2 Centaur launch.

- Many asteroids frequently return to Earth's vicinity. For example, the asteroid 2022 NX1 became a mini-moon in 1981 and again in 2022, with another return expected in 2051.

- The asteroid 2006 RH120 orbited Earth for an entire year, from July 2006 to July 2007.

- Some researchers believe this phenomenon is so consistent that Earth may always have a mini-moon orbiting somewhere nearby.

Can we witness 2024 PT5 with our naked eye?

Despite its 57-day close flyby of Earth, the asteroid will be difficult to spot due to its small size, measuring just 33 feet (10 meters) wide. According to NASA, 2024 PT5 has an absolute magnitude of 27.593, making it too dim to see, even with a telescope.

For comparison, the dimmest objects visible to the naked eye at night have a magnitude of around 6.5, and a 12-inch telescope can detect objects with a magnitude of about 16 or 17. This means amateur astronomers won't be able to observe 2024 PT5, as it would require a much more powerful telescope.