A new mini-moon—referred to scientifically as 2024 PT5—is set to make a two-month orbit around the Earth this fall. Here’s what you need to know about the rare occurrence.

When approaching Earth, asteroids tend to do one of two things: Most of the time, they miss. Sometimes, they hit, leaving a bright streak in our planet’s sky or a gruesome new wound in its crust. But very rarely, asteroids are captured by Earth’s gravity and pirouette around the planet, becoming, in effect, a moon — albeit an ephemeral one.