In a rare astronomical event, Earth is set to capture a temporary moon between September 29 and November 25. The new addition, designated as 2024 PT₅, is an asteroid originating from the Arjuna asteroid group.

Measuring approximately 30 feet in diameter, 2024 PT₅ will be ensnared by Earth’s gravitational pull for a span of 57 days. Although small — making it invisible to the naked eye or small telescopes — it will be detectable by larger telescopes.

NASA defines moons as “naturally formed bodies that orbit planets.” However, astronomers categorize mini-moons differently. These are asteroids or comets that are temporarily captured by a planet’s gravity. While mini-moons are relatively common, those large enough to be observed are rare.

Notably, 2024 PT₅ is only the fifth mini-moon of its kind to be detected around Earth. The object is classified under “temporarily captured flybys,” meaning it will not complete a full orbit around the Earth before resuming its trajectory around the Sun. In contrast, “temporarily captured orbiters” do make at least one full orbit around our planet before moving on.

Out of Earth’s five recorded mini-moons, two have been “temporarily captured orbiters,” while the remaining — including 2024 PT₅ — are categorized as “temporarily captured flybys.”