Researchers from Spain have discovered a kind of second moon orbiting around Earth. Known as Apollo asteroid 2025 PN7, it was detected by the Pan-STARRS observatory in Hawaii on August 2nd, 2025. According to current calculations, it has been accompanying the Earth since the 1960s—and it’s expected to stay that way for the next 60 years.
However, it must be said that 2025 PN7 is not a real moon but rather something called a quasi-moon. A quasi-moon is an asteroid that orbits around the sun but in such a way that it looks like it’s orbiting around a planet from the perspective of that planet. In this case, 2025 PN7 looks like it’s orbiting Earth but isn’t bound by Earth’s gravitational pull.
2025 PN7’s behavior is consistent with those in the Arjuna asteroid belt, which are a group of near-Earth asteroids with Earth-like orbits, making it an Arjuna asteroid. (Arjuna asteroids are a subgroup of Apollo asteroids.) The first such asteroid was discovered as early as December 1991 by the Spacewatch Project, which was initially thought to be an interstellar space probe. Scientists are now aware of over 100 such asteroids.
Why did it take so long for the quasi-moon 2025 PN7 to be discovered?
2025 PN7 is very small with a diameter around 15 to 30 meters and a distance to Earth of around 384,000 kilometers (sometimes even as close as 300,000 kilometers depending on the orbit). This corresponds roughly to the distance of our own moon, except much smaller in size.
In addition, the asteroid is faint and can only be detected with current telescopes when it comes close to the Earth. (Funnily enough, the researchers have also spotted 2025 PN7 in previously archived images going back to 2014.) 2025 PN7 poses no danger to Earth.
This article originally appeared on our sister publication PC-WELT and was translated and localized from German.
