Earth's New 'Mini-Moon' 2024 PT5 Is Actually A Small Asteroid -- But Don't Worry About It Getting Loose

 

                                Artist's depiction of "mini-moon"  2024 PT5

The new mini moon, 2024 PT5, was first spotted in August by astronomers at Complutense University of Madrid using a powerful telescope located in Sutherland, South Africa. But since last Sunday it will be temporarily trapped by our Earth's gravity and orbit the globe - but only for about two months.

 In fact, this interloper is actually an asteroid about the size of a school bus at 33 feet (10 meters). As for posing any danger in striking our planet, no not at all. Even if it did somehow break loose and impact our planet, it would still have much less than the explosive Chelyabinsk event in February, 2023.  That small asteroid was at least 66 feet in diameter by way of comparison.

In any case, these short-lived mini moons are likely more common than we realize. For example, the 2022 NX1 asteroid joined Earth's orbit in 1981 and 2022, according to BBC News.  According to one astronomer familiar with the objects:

"This happens with some frequency, but we rarely see them because they're very small and very hard to detect. Only recently has our survey capability reached the point of spotting them routinely."

The discovery by Carlos de la Fuente Marcos and Raúl de la Fuente Marcos was published in The Research Notes of The American Astronomical Society:

A Two-month Mini-moon: 2024 PT5 Captured by Earth from September to November - IOPscience

Lead author Carlos de la Fuente Marcos noted in an email:

"This one won't be visible to the naked eye or through amateur telescopes, but it can be observed with relatively large, research-grade telescopes," 

It takes about 27 days for the moon to make one complete orbit around the earth. The asteroid disguised as a mini-moon will travel with us for nearly 57 days, completing almost one full orbit of Earth. After that, the rock will break free from our gravitational grasp on November 25, returning to its path around the Sun. It's expected to pass by again in 2055.

It might sound extraordinary to get a second moon, but according to NASA it’s quite common for asteroids and other space rocks to enter the gravitational pull of the earth. 

"Why didn't anyone know about this before? Like in the 19th century?"

Well, because the objects, like PT5 at 33' diameter, were simply too tiny to be picked up by the telescope of the time.

And so, unlike the moon, the asteroid 2024 PT5 won't be visible to the casual stargazer because of its size. It’ll be too small and too dim to be seen without a powerful telescope.

Want a moonlight dinner? Stick to when our own original Moon shines bright like at next Full Moon. In the meantime, rest easy as there's almost zero chance of getting loose and whacking our planetary abode.

See Also:

The Earth Now Has Two Moons—Here's How to See Them (sunset.com)

And:

Good News: Close encounter with a second moon (nbcnews.com)