Astronomers from the University of Hawaii have made a significant discovery, identifying a new quasi-moon known as 2025 PN7. This cosmic object, which orbits near Earth, was detected over the summer of 2025 and is believed to measure between 18 and 36 meters in width, comparable in size to a small building.
Unlike the Moon, 2025 PN7 is not gravitationally tethered to Earth. Instead, it follows a path around the Sun that closely mirrors Earth”s orbit, resembling “two runners on a track, moving at the same pace, close together but never directly connected,” according to the astronomers involved in the observation.
“This discovery adds a fascinating new member to Earth”s extended neighborhood,” they noted, emphasizing its significance.
Characteristics and Orbit of 2025 PN7
Researchers estimate that 2025 PN7 has likely been traveling alongside Earth for approximately 60 years. If it maintains its current orbit, it is expected to remain in this position until 2083, after which it will drift away into the vastness of space. The distance between this quasi-moon and Earth varies greatly, influenced by the gravitational forces of the Sun and nearby planets. When it is closest, it can approach within 4 million kilometers, which is about ten times the distance to the Moon. Conversely, at its farthest, it can extend out to 17 million kilometers.
The team at the Pan-STARRS observatory in Hawaii first identified 2025 PN7 during a standard telescope survey. Initially, it appeared as a faint dot against the starry backdrop, but further observations confirmed its synchronized movement with Earth as both bodies orbit the Sun. After weeks of diligent monitoring, NASA validated that Earth had gained this temporary companion.
Understanding Quasi-Moons
Currently, astronomers have confirmed only eight quasi-moons around Earth and other celestial bodies, making the study of each one crucial for understanding asteroid dynamics and gravitational interactions. Notably, 2025 PN7 is recognized as the smallest and least stable of these quasi-moons, which complicates its observation due to its limited visibility during specific times and angles.
Despite its diminutive size, the quasi-moon presents a valuable opportunity for scientific research. Space expert Carlos de la Fuente Marcos highlighted its potential by stating, “Small, nearby asteroids could serve as ideal testing grounds for future unmanned space missions.” While 2025 PN7 will not be visible to the naked eye like the Moon, it will continue to act as a quasi-satellite for the next several decades, accompanying Earth on its journey through the solar system.
