Named for the Hawaiian phrase “oscillating fragment,” Kamo'oalewa is about the size of a Ferris wheel. Although it follows an elliptical orbit that appears to move in sync with Earth, it actually lies outside our planet's gravitational influence, ruling out this visitor as a true minimoon.

In June, NASA also tracked the approach of asteroid 2011 UL21 and discovered a binary star system – a smaller asteroid, called a moonlet, orbited it from a distance of about three kilometers. Such precise moon hunting is a major advance compared to 1991, when VG, the first mini-moon to be discovered, gained notoriety as people argued about whether it was a natural object or more likely of extraterrestrial origin.

The true meaning of PT5 2024 and asteroid research

Although the Earth-Moon system is no stranger to short-lived (and relatively quiet) space guests, experts can say with certainty that we won't be getting another satellite as large or cosmically important as our moon in the near future. Pretty small objects have been orbiting near us for billions of years and we never really noticed, says Statler, because nothing bad happened as a result. “That's a good indication that this doesn't play a major role in terms of affecting life on Earth,” he says.

In a stable configuration, two moons of comparable size would also completely alter the tides of the oceans and would also likely change scientists' knowledge of the history of astronomy, including how these moons formed. But even that almost certainly won't happen soon, if the last few billion years are any indication.

Why is PT5 2024 getting so much attention? Andrew Rivkin, a planetary astronomer at Johns Hopkins University's Applied Physics Laboratory, says that may be because the appearance of this asteroid is one of the first times that scientists have been able to predict the presence of a minimoon in advance. “It’s a great demonstration of our ability to find things and predict where they go.”