Earth’s moon will soon have a friend: a “mini moon.” The mini moon is actually an asteroid the size of a school bus, 33 feet (10 meters) high. When it flies past Earth on Sunday, it will be temporarily captured by our planet’s gravity and enter orbit around it, but this will only last for about two months.

The space rock (2024 PT5) was first detected in August by astronomers at the Complutense University of Madrid using a powerful telescope located in Sutherland, South Africa.

These short-lived mini-satellites are probably more common than we think, said astronomer Richard Binzel of the Massachusetts Institute of Technology. The last known one was discovered in 2020.

“This happens with some frequency, but we rarely see them because they are so small and so hard to detect,” he said. “Only recently have our research capabilities reached a level where we can detect them on a regular basis.” The discovery of Carlos de la Fuente Marcos and Raúl de la Fuente Marcos was published by the American Astronomical Society.

It cannot be seen with the naked eye or amateur telescopes, but “can be observed with relatively large scientific-grade telescopes,” Carlos de la Fuente Marcos said in an email.

Binzel, who was not involved in the research, said it was not clear whether the space rock originated from the asteroid or “an exploding piece of the moon.”

The minimoon will orbit the earth for almost 57 days, but will not complete a full orbit. It will leave Earth on November 25 and continue its journey alone in space. It is expected to pass again in 2055.