A so-called mini-moon of Earth that has been lingering in the heavens since September will begin a journey towards the sun on Monday as it prepares to disappear until 2055.
The school-bus-sized asteroid known as 2024 PT5 might actually be a huge boulder that broke from the moon after another space rock crashed into it centuries ago, astronomers say.
Currently 2m miles (3.2m km) from Earth, about nine times farther than the distance to the moon, the asteroid never quite came close enough to be captured by the planet’s gravity.
But its farewell pass will bring it as close as 1.1m miles in January for a final look before the sun’s gravitational pull hauls deeper into space.
The mini moon’s small size, about 33ft wide, and distance meant it was never visible to humankind’s naked eye, only through powerful telescopes. Nasa has been tracking the asteroid through its deep space network since it was first spotted through a South African-based telescope belonging to the University of Hawaii in August.
It has been a “distant companion” of Earth since then, Nasa said, and studies have determined it was not a man-made object.
“Given the similarity between asteroid 2024 PT5’s motion and that of our planet’s, scientists at Nasa’s center for near Earth object studies suspect that the object could be a large chunk of rock ejected from the moon’s surface after an asteroid impact long ago,” Josh Handal, program analyst for the space agency’s planetary defense coordination office, wrote in a briefing.
“Rocket bodies from historical launches can also be found in such Earth-like orbits, but after analysis of this object’s motion, it has been determined that 2024 PT5 is more likely of natural origin.”
It has been following a horseshoe-shaped path around Earth for the last two months, and will be picking up velocity exponentially once the sun’s gravitational pull takes full effect after Monday. Its speed during its close pass in January will be at least twice that from September, astrophysicist Raul de la Fuente Marcos of Madrid’s Complutense University told the Associated Press.
Nasa will track the asteroid for more than a week in January using the Goldstone solar system radar antenna in California’s Mojave desert.
When it returns in 2055 after an orbit of the sun, the asteroid will once again make a temporary and partial lap around Earth.
