Our planet is set to gain a second, 'mini-moon' tonight (29 September), which will stick around for a couple of months. It is part of the Arjuna asteroid belt, which is not too far from Earth by space terms, just 2.8 million miles (4.5 million kilometres) away.

When will Earth get a new mini moon? And how long will it be there for? Here's everything you need to know about the asteroid including how visible it will be.

A mini-moon is a “temporarily captured orbiter” if it completes at least one full orbit of the Earth before returning to its usual orbit around the Sun. If a mini-moon is captured by Earth’s gravity but doesn’t make it around for a full orbit, it’s a “temporarily captured flyby” instead.