Astronomers have discovered a tiny quasi-moon near Earth, called 2025 PN7, which has likely stayed close to our planet for around 60 years. Unlike the Moon, quasi-moons do not directly orbit Earth. Instead, they enter into a kind of resonance with Earth’s orbit, making it appear as if they are moving with our planet. These small asteroids are part of a group called Arjunas, which share Earth-like orbits around the Sun.

The discovery was made by astronomers at the Pan-STARRS observatory in Hawaii on August 2, 2025, and the findings were recently published in Research Notes of the AAS. Using orbital data from NASA’s JPL Horizons system and Python tools, the team analysed 2025 PN7’s path and compared it to other Arjunas and known quasi-satellites.

Scientists found that 2025 PN7 has been in a quasi-orbit for about 60 years and will likely remain nearby for another 60 years. While this is relatively short, other quasi-moons like Kamo’oalewa have much longer near-Earth orbits, around 381 years.

What are quasi-moons, and why they matter

The study explains, "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."

Unlike mini-moons, which temporarily orbit Earth, quasi-moons only appear to do so. Currently, there are six other known quasi-moons, including 164207 Cardea, 469219 Kamo’oalewa, 277810 (2006 FV35), 2013 LX28, 2014 OL339, and 2023 FW13.

Astronomers hope that tracking quasi-moons like 2025 PN7 will help in planetary defence, future space missions, and possibly asteroid mining in the distant future. This discovery highlights how many small near-Earth objects are still waiting to be found, offering important insights into the dynamics of our cosmic neighbourhood.

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