Earth to bid farewell to its temporary mini moon on Monday

A so-called “mini moon” that’s been orbiting Earth for the last couple of months is about to disappear off into our solar system again.

The near-Earth asteroid, officially called 2024 PT5, was first spotted in early August by the NASA-funded Sutherland, South Africa, telescope of the University of Hawaii’s Asteroid Terrestrial-impact Last Alert System (ATLAS). The term “mini moon” emphasizes the rock’s small size — it’s thought to be about 10 meters (33 feet) wide — and also its temporary nature as it will never be permanently captured in Earth’s gravitational field.

The rock’s orbital distance from Earth has been about nine times that of the moon’s distance from our planet, and it never posed a risk to Earthlings.

“Given the similarity between asteroid 2024 PT5’s motion and that of our planet’s, scientists at NASA’s Center for Near Earth Object Studies (CNEOS) believe that the object could be a large chunk of rock ejected from the moon’s surface after an asteroid impact long ago,” NASA said.

After November 25, asteroid 2024 PT5 will leave Earth’s vicinity and continue its journey around the sun. The timing of the rock’s exit is influenced by the gravitational interactions between Earth, the moon, and the sun, and it is the gravitational forces exerted by these celestial bodies that are causing the asteroid to be pulled back into its original path around the sun.

Professor Carlos de la Fuente Marcos, one of those involved in the discovery of 2024 PT5, told Space.com in September — just ahead of the rock’s arrival — that it belongs to the Arjuna asteroid belt, a secondary asteroid belt made of space rocks that follow orbits very similar to that of Earth at an average distance to the sun of about 93 million miles (150 million kilometers). Commenting on 2024 PT5 becoming a temporary companion of Earth, he added, “You may say that if a true satellite is like a customer buying goods inside a store, objects like 2024 PT5 are window shoppers.”

Besides a close pass in January next year, 2024 PT5 won’t be dropping by our neighborhood again until 2055, and after that, in 2084.