Earth Bids Farewell to 'Mini Moon' Asteroid Set for Return Visit in 2055

Planet Earth is saying goodbye to a cosmic hitchhiker—a 33-foot asteroid that’s been casually tagging along as a "mini moon" for the past two months. But don’t worry, it’s not forever. This harmless rock, officially named 2024 PT5, will be back for a quick hello in January before making a grander return in 2055.

On Monday, the asteroid will break free from Earth’s gravitational grasp, succumbing instead to the sun’s stronger pull. While not a true moon—it was never fully captured by Earth’s gravity—NASA still deems it "an interesting object" worth keeping tabs on. And really, who wouldn’t want to know more about what could be a chunk of the moon itself, possibly ejected by a dramatic asteroid impact?

Astrophysicist brothers Raul and Carlos de la Fuente Marcos, from Complutense University of Madrid, are the duo who tracked its "mini moon behavior." Using telescopes in the Canary Islands, they’ve been meticulously observing 2024 PT5 as it drifted along its peculiar horseshoe-shaped path since late September.

Currently more than 2 million miles away, the asteroid is too small and faint to spot without some seriously powerful telescopes. But in January, it’ll come within about 1.1 million miles of Earth—practically a cozy neighbor in cosmic terms before it hightails it further into the solar system. For perspective, that’s still nearly five times farther away than the moon.

First detected in August, the asteroid made its semi-close approach to Earth in September, briefly caught in our planet’s gravity. NASA plans to observe it in January using the Goldstone solar system radar antenna in California’s Mojave Desert, part of its Deep Space Network. Scientists aim to gather more data about its speed, trajectory, and composition.

By January, 2024 PT5 will be zooming at more than twice the speed it had in September, making it too fast to stick around. Still, current data suggests it might attempt another fleeting lap near Earth in 2055, but that’s a story for future Earthlings to tell.