Ephemeral Earth companions may be very common, according to Michele Bannister, an astronomer at the University of Canterbury in Christchurch, New Zealand.

“They are orbiting roughly the same space that we are, and some will get into the right spot where it can nudge into a ballet with us. And then it’s like any dance: you do a couple spins together, and go your separate ways,” she says. “There’s something beautifully transient about it.”

Astronomers at the Minor Planet Center, an international body that tracks asteroid discoveries, announced the find on Tuesday. With only a few nights of data, it’s too early to say exactly what 2020 CD3 is made of. But many astronomers are convinced it is not a leftover from a rocket launch or other human activity.

It might be the size of a small car. “It would probably fit in a bedroom, even in San Francisco or New York,” says Alessondra Springmann, an astronomer at the University of Arizona.