For a brief, but exciting, time last year, Earth had two moons. A small asteroid lingered close to our planet in its orbit around the Sun, temporarily caught by Earth’s gravity to become a far away mini-moon. A closer look at the space rock reveals a rather familiar origin: Earth’s mini-moon might actually be a broken-off piece of our regular Moon.

The asteroid is about 33 feet (10 meters) across and poses no danger to Earth. It joins another known lunar asteroid discovered in 2016 known as 469219 Kamo’oalewa. Scientists hope that as telescopes become more powerful, we will be able to detect more bits of the Moon that have been blasted free in ancient impacts.

Earth's temporary asteroid friend last year was a chunk of its real moon that had been blasted into space thousands of years ago, scientists find.

A near-Earth object was likely ejected into space after an impact thousands of years ago. Now it could contribute new insights to asteroid and lunar science.

The sun’s light exerts a tiny force called “solar radiation pressure” on objects in space. Lightweight human-made debris, like hollow rocket parts, gets pushed around more easily, like a tin can in the wind. Natural objects like asteroids are much denser and less affected.