Earth is set to play host to a “mini-moon” this week, as a small asteroid – about the length of a double-decker bus – enters the planet’s orbit. The temporary guest, called 2024 PT5, is set to arrive on September 29 and is expected to befriend the regular Moon for around two months.
Daniel Brown, associate professor in astronomy at Nottingham Trent University, explained that a mini-moon is a small object orbiting another solar system body, which could be a rock or a mixture of rock, dust, and ice. The mini-moon belongs to the Arjuna asteroid belt, a group of space rocks in the solar system that revolves around the Sun.
2024 PT5 was first discovered at a distance of 353,200 miles (568,500 km). Prof Brown stated that the mini-moon will orbit Earth for 57 days before eventually leaving due to having too much energy to stay in Earth’s gravitational pull. However, Earth will not bid farewell to 2024 PT5 forever, as scientists predict it will be captured again by Earth’s gravity around 2055.
Notably, this is not the first time Earth has had a mini-moon, as four years ago, scientists identified another mini-moon, called 2020 CD3, which orbited the Earth for over a year. 2024 PT5 will not be visible to the naked eye and can only be seen through telescopes used by professional astronomers.
Prof Brown highlighted that mini-moons are fairly common but observing them is challenging due to their small size, faint appearance, and fast movement. Mini-moons like 2024 PT5 are part of near-Earth objects (NEOs), a group of space rocks that regularly pass by Earth. While astronomers monitor NEOs for any potential threat to Earth, experts believe 2024 PT5 will not pose such a risk.
In conclusion, the arrival of 2024 PT5 offers a fascinating glimpse into the complex orbits of small bodies in our solar system, briefly crossing paths with Earth before continuing on their elliptical path around the Sun, only to return for another meeting with Earth in the future.