Astronomers have discovered the last quasi-moon of the Earth

has land Added its 7th confirmed pseudo-moon. This is asteroid 2025 PN7, a small Apollo-type asteroid that was detected by its brightness alone in August thanks to Hawaii’s Pan-STARRS 1 telescope.

After analyzing the trajectory, scientists concluded that this object has a 1:1 resonance with the Earth. In other words, it revolves around the sun at the same time as our planet. From a distant perspective, this coincidence makes it look like Earth has been joined by a small asteroid—as if it had an extra moon.

Unlike the Moon, quasi-moons are not gravitationally bound to Earth. They are cosmologically fleeting companions that follow their path around the Sun. Only at certain times do they come close enough to appear closed. In the case of 2025 PN7, its minimum distance is 299,000 km, while at its farthest point it can reach 17 million km. For comparison, the Moon remains at an average distance of 384,000 km from Earth.

According to the article published in AAS Research Notes, This asteroid has been in the quasi-satellite phase since 1965 and is expected to remain in this phase for 128 years. Some researchers estimate that 2025 PN7 will finally disappear in 2083.

Why does Earth have quasi-moons?

So far, seven bodies have been confirmed that appear to accompany the planet in its orbit. Astronomers believe that more may be discovered in the future. Earth is a natural quasi-lunar reservoir because Earth’s orbit is similar to that of some nearby bodies that reside in the so-called Arjuna group of asteroids, a population that has only recently begun to be studied in more detail.

The Arjuna Group does not form a ring like the asteroid belt between Mars and Jupiter, but consists of a legion of near-Earth rocks orbiting the Sun in a similar path to our planet. Sometimes, some of these asteroids cross our path and are classified as quasi-moons or small moons depending on their orbital dynamics.

The quasi-lunar moon 2025 PN7 is located not far from Earth in the Arjuna asteroid group.Image: Simi