An asteroid that some are calling Earth’s next “mini-moon” was discovered by a University of Hawaiʻi-operated telescope.
The 33-foot wide asteroid, called 2024 PT5, was detected on August 7, by the NASA-funded UH’s Asteroid Terrestrial-impact Last Alert Survey (ATLAS) telescope in Sutherland, South Africa, one of four global telescopes operated by UH’s ATLAS system that search for dangerous asteroids that might impact the Earth.
Earth’s gravitational pull will snag 2024 PT5 between September 29 and November 25, before it escapes the planet’s orbit and continues its journey around the Sun. UH experts describe the orbit of 2024 PT5 as “Earth-like,” meaning that the asteroid is nearly the same distance from the Sun as the Earth and spends all of its time along a path very similar to Earth’s orbit.
Every few decades, the asteroid comes close enough to Earth to be temporarily “captured,” meaning that it will be loosely bound to Earth’s gravity without being in orbit around the Earth. This capture episode will last for two months before the asteroid escapes the Earth’s gravitational field until the year 2055, when the next capture is predicted to occur.
While there is no official definition of a “mini-moon,” 2024 PT5 comes only within about one million miles from Earth, four times farther than the Moon, and is so tiny that it can only be seen with a powerful telescope. Even though its behavior is not very “moon-like,” it is the latest of a handful of objects that have been temporarily captured by the Earth’s gravity. Such objects could someday present opportunities for sample retrieval or asteroid mining.
“The discovery of 2024 PT5 by our ATLAS telescopes is an important reminder that there are countless small objects orbiting the Sun, and some of them can temporarily become Earth’s companions,” said Larry Denneau, UH Institute for Astronomy astronomer and ATLAS co-principal investigator. “While this object poses no threat whatsoever to our planet, it showcases the invaluable work our team is doing to vigilantly monitor the skies and detect these objects before they make a close approach.”
The unusual temporary capture aspect of 2024 PT5’s orbit was revealed after the object’s discovery by a study published in Research Notes of the American Astronomical Society.
The four-telescope ATLAS system is the first line of defense in surveying hazardous asteroids capable of monitoring the entire dark sky every 24 hours. Read this UH News story for more about ATLAS.
