For months space enthusiasts were fascinated by a small asteroid that was pulled by Earth's gravity and was fondly referred to as Earth's second Moon. A new study now reveals could have indeed been part of our own Moon.
Near-Earth object 2024 PT5 became the centre of attraction when Earth's gravity captured it for months in September 2024. About 33 feet (10 meters) wide, the asteroid did not pose a hazard to Earth but had one thing in common with our planet - a matching orbit around the Sun.
A new study in the Astrophysical Journal Letters reveals the local origins of the asteroid. Researchers said that the asteroid appears to be composed of rock broken off from the Moon’s surface and ejected into space after a large impact.
“We had a general idea that this asteroid may have come from the Moon, but the smoking gun was when we found out that it was rich in silicate minerals — not the kind that is seen on asteroids but those that have been found in lunar rock samples,” said Teddy Kareta, an astronomer at Lowell Observatory in Arizona, who led the research.
This celestial visitor dubbed a "mini-moon," was first detected on August 7 by NASA's Asteroid Terrestrial-Impact Last Alert System (ATLAS).
Originating from the Arjuna asteroid belt, a collection of space rocks that share similar orbits with Earth, 2024 PT5 did not complete a full revolution around our planet.
Instead, its path was slightly altered by Earth's gravity, before it continued its journey through the solar system.
To achieve mini-moon status, an asteroid must approach Earth at a relatively slow speed. This allows our planet's gravity to capture the object temporarily, creating a short-lived natural satellite.
“It looks like it hasn’t been in space for very long, maybe just a few thousand years or so, as there’s a lack of space weathering that would have caused its spectrum to redden,” Kareta added.
To rule out 2024 PT5 being space junk, scientists analysed its motion. Their precise calculations of the object’s motion under the force of gravity ultimately enabled them to search for additional motion caused by solar radiation pressure.
The discovery of 2024 PT5 doubles the number of known asteroids thought to originate from the Moon. Asteroid 469219 Kamo’oalewa was found in 2016 with an Earth-like orbit around the Sun, indicating that it may also have been ejected from the lunar surface after a large impact.
Source: India Today