‘That’s no moon!’ Scientists identify new ‘mini-moon’ that will orbit Earth for months

The Earth’s moon will get a sidekick at the end of September: a 33-foot-long asteroid scientists call a “mini-moon.”

The tiny asteroid, which has been named 2024 PT5, was discovered on August 7 by scientists who routinely monitor the universe for anything out of the ordinary using a powerful telescope called the Asteroid Terrestrial-impact Last Alert System, or ATLAS.

Before you start worrying about a Deep Impact situation, never fear. This little guy isn’t going to crash into the Earth. Instead, 2024 PT5 will simply tag along in our orbit for a few months before returning to the asteroid belt from which it came.

About 2024 PT5

Professor Carlos de la Fuente Marcos was one of the scientists who discovered the mini-moon. Speaking to Space.com, he explained, “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). Objects in the Arjuna asteroid belt are part of the near-Earth object population of asteroids and comets.”

In layperson’s terms, the Arjuna asteroid belt is always orbiting the sun, just as Earth does. Every so often, a little piece of the belt breaks away and is drawn into the Earth’s own gravitational pull. The asteroid then orbits Earth itself, becoming a “mini-moon,” but our gravity can’t keep it with us forever.

2024 PT5 will join Earth’s orbit around September 29 and will return to the Arjuna asteroid belt around November 25. It will not make a complete orbit around the Earth, but still qualifies as a “mini-moon” event according to NASA.

Will we be able to see the mini-moon?

Sadly, this mini-moon event will not be visible to the majority of space enthusiasts. It will take a powerful, professional-grade telescope to spot the small, dim object in our orbit. “The object is too small and dim for typical amateur telescopes and binoculars,” Professor Marcos explains. “However, the object is well within the brightness range of typical telescopes used by professional astronomers.”

Are mini-moon events rare?

Short-duration mini-moon events like this one, which involves a small body (like an asteroid), are relatively common, occurring a few times each decade. Longer capture episodes are much rarer, happening once every decade or two.

The last time Earth had a mini-moon event was the 2022 NX1 asteroid. We first saw that mini-moon in 1981, and it’s expected to return to our orbit in 2051. All things being equal, we will see the 2024 PT5 return to our orbit as soon as January before winging off into space and coming back in 2055.

What can we say? It’s not easy having such a magnetic personality!