Astronomers from the University of Hawaii discovered 2025 PN7 using the Pan-STARRS 1 telescope in Haleakalā last August, identifying a small asteroid measuring 18 to 36 meters wide that has been accompanying Earth for approximately 60 years.
The object is classified as a quasi-moon or quasi-satellite, meaning it orbits the Sun in near-perfect synchronization with Earth in a 1:1 resonance rather than being gravitationally bound to our planet like the Moon.
This Arjuna asteroid—part of a group of over 100 small bodies with Earth-like orbits—approaches as close as 4 million kilometers (ten times the Moon's distance) and retreats as far as 17 million kilometers during its orbital dance.
Scientists used precise calculations from NASA's Jet Propulsion Laboratory Horizons data system and Small-Body Database to confirm its semimajor axis of 1.003 astronomical units, placing it securely in the Arjuna family alongside other known quasi-moons like Kamo'oalewa, Cardea, and 2023 FW13.
The quasi-moon will remain Earth's cosmic companion until approximately 2083 before departing, and researchers believe studying such objects could improve early warning systems for potentially hazardous asteroids while serving as accessible targets for future space missions.
