Reading: Earth has another quasi-moon – and no one realised for decades

Earth has another quasi-moon – and no one realised for decades

Last updated: 2025/09/19 at 2:18 AM

News Room Published 19 September 2025

The Moon is not the only thing hanging around the Earth. As well as the hundreds of satellites circling around us, we also have a few quasi moons and mini-moons. And now, researchers have found another quasi-moon – which seems to have been there for over 60 years already. This makes up the number of quasi-satellites of our planet to 8 (Picture: Getty)

Although it may seem that these ‘moons’ are orbiting the Earth, they’re actually orbiting the Sun at the same time as our planet, which is making them look like moons to the Earth. The newest one, 2025 PN7, is small and is roughly just ten metres wide. It’s also keeping its distance and does not come closer than several million kilometres to Earth (Picture: Getty)

The team discovered that 2025 PN7 had been in a quasi-orbit for about 60 years already and would likely be nearby for another 60 or so years before departing, which gives it around 130 years with the Earth. In terms of quasi-satellites, this timeframe is short as the quasi-moon Kamo’oalewa has an expected near-Earth orbit of around 381 years (Picture: Getty)

The authors, who published in Research Notes Of The American Astronomical Society, wrote: ‘Over three decades later, it is now widely accepted that such objects are natural and constitute a secondary asteroid belt that occupies the region in which the Earth–moon system orbits around the sun, defining the Arjuna dynamical class. The Arjunas with the most Earth-like orbits can experience temporary captures as mini-moons of our planet’ (Picture: Getty)

The moon poses no threat to Earth, and is known as the Arjuna asteroid. It is currently in the constellation Piscis Austrinus (the ‘Southern Fish’), which is best seen from the Southern Hemisphere. It’s orbiting between 2.8 million miles and 37.2 million miles from Earth. However, they do feel a slight pull from the Earth, despite the fact they are orbiting the Sun in step of the Earth (Picture: Getty)

Although the Earth has one permanent natural satellite, there are a few natural forming rocks that seem to orbit the Earth. But these quasi-satellites are moving in sync with the Earth in a 1-1 resonance. However, mini-moons are temporarily caught by Earth’s gravity. For example, an asteroid called 2024 PT5 orbited the Earth for just 57 days in 2024 before it went back to its solar orbit (Picture: Getty)

The most famous quasi-satellite is Kamoʻoalewa, also called 2016 HO3, discovered in 2016. It is around 130–330 feet (40-100 meters) in diameter, and its name in Hawaiian means ‘oscillating celestial object’ as it reflects the looping orbit that always keeps it near Earth. There are six other known quasi-moons: 164207 Cardea (2004 GU9), 469219 Kamo’oalewa (2016 HO3), 277810 (2006 FV35), 2013 LX28, 2014 OL339 and 2023 FW13 (Picture: Getty)

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