Earth to get a mini-moon for two months, but what is it? | Space News | Space

From late September until late November this year, a “mini-moon”, called 2024 PT5 by the astrologers who spotted it approaching will be orbiting the planet. Although this mini-moon cannot be seen by the naked eye – it is just 10 metres (33ft) in diameter – it can be viewed through a high-powered telescope.

Mini-moons are asteroids which have been pulled by the Earth’s gravity into orbit around the planet and remain there until they become dislodged and move away again. The length of time these mini-moons remain in orbit depends on the speed and trajectory with which they approach the Earth.

Most mini-moons that enter Earth’s orbit are hard to see because they are too small and not bright enough to be seen against the backdrop of the darkness of space.

What, exactly, is a mini-moon?

Mini-moons are extremely rare. Asteroids are usually pulled into Earth’s orbit by the gravity of the planet as rarely as once in 10 to 20 years, but a few more have appeared in recent years. They can remain in the exosphere, which is roughly 10,000km (6,200 miles) above the surface of the Earth.

On average, mini-moons remain in Earth’s orbit for anything from a few months to two years with the asteroid eventually breaking away from Earth’s gravitational pull, then moving back into space to resume a trajectory away from the planet.

Similar to other rocky bodies in space,…