A new quasi-moon, designated 2025 PN7, has been identified by astronomers, who believe it has been orbiting Earth undetected for approximately 60 years. This finding marks a significant addition to our understanding of celestial bodies in near-Earth space.
2025 PN7 is classified as a near-Earth asteroid that follows a solar orbit while remaining in close proximity to our planet. Similar to Earth, it completes its solar orbit in one year. Unlike temporary mini-moons that orbit Earth for short periods, such as 2024 PT5, 2025 PN7 is expected to remain in its near-Earth orbit for about another 60 years before transitioning into a horseshoe orbit due to the sun”s gravitational influence.
The discovery of this celestial body was made possible through observations from the Pan-STARRS observatory, located on the Haleakala volcano in Hawaii, on August 29. Researchers analyzed archival data, which indicated that 2025 PN7 has been in a stable orbit resembling Earth”s for decades.
According to Carlos de la Fuente Marcos, a researcher at the Complutense University of Madrid and author of the study published on September 2 in the journal Research Notes of the American Astronomical Society, the object has a faint and small profile, making it difficult to detect. “It can only be detected by currently available telescopes when it gets close to our planet, as it did this summer,” he explained.
During its closest approach, 2025 PN7 comes within approximately 186,000 miles (299,337 kilometers) of Earth, with an average distance of about 238,855 miles (384,400 kilometers) from our planet, according to NASA.
De la Fuente Marcos estimates the size of 2025 PN7 to be around 98 feet (30 meters) across, though estimates vary, with some suggesting it could be as small as 62 feet (19 meters). This makes it the smallest known quasi-moon orbiting near Earth.
Over time, 2025 PN7 oscillates between a more circular Earth-like orbit and a horseshoe orbit, which can extend its distance from our planet to about 185 million miles (297 million kilometers). The future trajectory of this quasi-moon is of interest, as it is anticipated to maintain its current orbit for another six decades before being influenced by solar gravity.
As for the composition of 2025 PN7, it remains uncertain. Dr. Teddy Kareta, an assistant professor in the department of astrophysics and planetary science at Villanova University, noted that it appears to be a natural rocky object. “While some near-Earth bodies may be artificial debris, we can often distinguish between natural and artificial objects based on their orbital behaviors over time,” he stated.
De la Fuente Marcos speculated that 2025 PN7 may originate from the Arjuna asteroid group, a collection of small asteroids that share similar orbits with Earth. He previously suggested that another mini-moon, 2024 PT5, could also be linked to this group, potentially derived from the moon”s surface.
Despite their close approaches, both quasi-moons and mini-moons like 2025 PN7 do not pose significant impact risks to Earth. The investigation into these celestial bodies, including missions like China”s Tianwen-2 to study Kamo”oalewa, could unlock further understanding of their origins and characteristics. According to De la Fuente Marcos, “These asteroids are relatively easy to access for unmanned missions and can serve as valuable test sites for planetary exploration technologies.”
