Earth’s “quasi-moon” or quasi-satellite?
Earth’s “quasi-moon” or quasi-satellite is an asteroid that shares a very similar orbit with Earth around the Sun, creating the illusion from our viewpoint that it orbits Earth like a moon. However, it is not a true moon because it is not gravitationally bound to Earth. Instead, it orbits the Sun but remains close to Earth over long periods due to this shared orbital path.
For example, asteroid 2025 PN7 is a newly confirmed quasi-moon that has been near Earth’s orbit for about 60 years and will remain so until roughly 2083. From Earth, it appears to orbit the planet, but it actually moves in an oval-shaped orbit around the Sun, sometimes closer to and sometimes farther from the Sun than Earth, which affects its relative speed and position. This causes it to seem as though it is moving around Earth, even though it essentially “shadows” Earth in its orbit.
Quasi-moons can transition between different types of co-orbital motions, such as quasi-satellite orbits, horseshoe orbits, or Trojan points, and are temporary companions, unlike Earth’s true moon which is permanently gravitationally bound.
The newly discovered asteroid 2025 PN7 is classified as Earth’s “quasi-moon” or quasi-satellite. Discovered by the Pan-STARRS observatory in Hawaii on August 2, 2025, it is a small near-Earth asteroid about 18-36 meters wide that shares Earth’s orbital path around the Sun in a synchronized 1:1 resonance. This means it does not orbit Earth directly like the natural Moon but follows a similar orbit around the Sun, appearing from Earth’s perspective as if it is orbiting the planet.
2025 PN7 has been orbiting alongside Earth since the 1960s and is expected to continue this complex orbital dance until approximately 2083. It belongs to the Arjuna class of asteroids, characterized by orbits very similar to Earth’s. Over this time, it stays relatively close, sometimes within about 299,000 km from Earth, but it is not gravitationally bound to Earth as a true moon is.
The asteroid’s discovery adds to the understanding that Earth has multiple quasi-moons or quasi-satellites — these are temporary companions that orbit the Sun in sync with Earth but are not permanent moons. 2025 PN7 is one of the smallest and least stable such companions known and will eventually drift away from Earth’s vicinity after 2083 due to gravitational influences.
2025 PN7 is a small asteroid that acts as a temporary quasi-moon of Earth, sharing Earth’s orbit around the Sun without being a true gravitational satellite, and will remain Earth’s companion until the late 21st century.
