The Earth now has another quasi-satellite, the asteroid Arjuna 2025 PN7, according to astronomers. A quasi-satellite is a small celestial body that orbits the Sun while remaining relatively close to a planet. From the perspective of that planet, the quasi-satellite appears to travel in an elliptical orbit.
The existence of Arjuna 2025 PN7 was first documented in August 2025 by the Mt. Lemmon Survey. Its orbit was initially mistaken for a Near Earth Object (NEO), which are asteroids or comets passing close to Earth’s orbit. However, further observation and analysis revealed that it was a quasi-satellite of Earth.
The Arjuna 2025 PN7 orbits the Sun once every 364.95 days, which is very close to Earth’s orbital period of 365.25 days. This similarity in orbital period allows the asteroid to maintain a stable position relative to Earth. The asteroid’s orbit is also highly tilted relative to the ecliptic plane, the imaginary plane that contains Earth’s orbit around the Sun. This tilt, combined with its elongated orbit, causes the asteroid to weave above and below the ecliptic plane, looping around Earth in the process.
The term “Arjuna asteroid” originates from a class of Near-Earth Asteroids (NEAs) named after 2156 Arjuna, an asteroid discovered in 1976. Arjuna asteroids have orbits that are similar to Earth’s, have relatively low velocities, and are easier to reach than other asteroids. This makes them potential candidates for future space missions.
The discovery of Arjuna 2025 PN7 adds to the small but growing list of known quasi-satellites of Earth. The first recognized quasi-satellite of Earth, (469219) 2016 HO3, was discovered in 2016. Since then, a few more have been identified. These quasi-satellites provide astronomers with unique opportunities to study these celestial bodies up close without having to send spacecraft vast distances into space.
It’s worth noting that while quasi-satellites remain near Earth for extended periods, they are not true satellites like the Moon. They do not orbit Earth, but rather orbit the Sun while maintaining a stable position relative to Earth. Over time, their orbits can change due to gravitational interactions with other celestial bodies, causing them to eventually move away from Earth.
In addition to their scientific value, quasi-satellites also have practical implications. Understanding their orbits can help scientists predict potential asteroid impacts and devise strategies for asteroid deflection. Moreover, their proximity to Earth makes them potential targets for future space mining operations.
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