Lunar guest: Earth is getting a second Moon for two months

Scientists aren't sure if 2024 PT5 is an asteroid. At roughly 10 meters in length, 2024 PT5 is difficult to spot without a telescope. Yet a new study reveals that for the next two months, 2024 PT5 will join our Moon in orbit around our planet, which means Earth will (temporarily) have a second moon, from September 29 to November 25.

Technically known as a "mini-moon event," celestial bodies like asteroids and comets will occasionally be captured by Earth's gravitational pull and temporarily orbit around our home. If they complete full revolutions of our planet while doing so, they are considered to be so-called "mini-moons." The leader researcher on the study, Universidad Complutense de Madrid professor Carlos de la Fuente Marcos, told Space.com that "The object that is going to pay us a visit belongs to the Arjuna asteroid belt, a secondary asteroid belt made of space rocks that follow orbits very similar to that of Earth at an average distance to the sun of about 93 million miles (150 million kilometers)."

The Arjuna asteroid belt contains a diverse array of asteroids and comets which periodically wander into our neighborhood. This is not the first time Earth has developed a surprise mini-moon. In 2020 an asteroid known as 2020 CD3 became a mini-moon, and two years later an asteroid called 2022 NX1 first became an Earth mini-moon in 1981 before returning in 2022. It is expected to reappear in 2051, while 2024 PT5 will return four years later in 2055.