Scientists have discovered the origins of an asteroid the size of a school bus that has been hanging out in the fringes of our orbit for two months.
Asteroid 2024 PT5 was dubbed Earth’s temporary ‘second moon’ because of its size and lingering presence so close to our planet.
Astronomers collected data on the asteroid as it circled Earth, finding it may be a chunk of our moon that was broken off in one of the collisions that left the lunar surface marred by craters.
The leading theory of lunar formation is the ‘giant impact hypothesis,’ which posits that the moon is actually an enormous, orbiting hunk of Earth.
According to this theory, our planet collided with a Mars-sized planet roughly four billion years ago, and this triggered an explosion of material from Earth that shot into space and eventually condensed to form the moon.
If the giant impact hypothesis and the analysis of Asteroid 2024 PT5’s origin are correct, that would mean our true moon is the parent of this mini moon, and Earth is its grandparent.
The second moon will begin its journey away from Earth today as it gets pulled out into space by the sun’s gravitational force.
‘There are multiple lines of evidence suggesting that this asteroid may have a lunar origin,’ Carlos de la Fuente Marcos, study lead author and a professor at the Universidad Complutense de Madrid, told Space.com.
‘Current research favors its rapid rotation with a rotational period under one hour, to be expected if 2024 PT5 is either a large boulder from the surface of the moon or a fragment from a larger object.’
He and his brother, Raul de la Fuente Marcos the Universidad Complutense de Madrid, identified the asteroid’s mini moon behavior.
As it traveled around the outer-edge of Earth’s orbit, the astrophysicists used telescopes in Spain’s Canary Islands to collect hundreds of observations of the asteroid.
They analyzed its spectra, or the range of electromagnetic wavelengths that it emits. This data indicated that the asteroid’s chemical composition matches that of lunar material previously brought back to Earth.
The researchers’ findings are currently available on the preprint server arXiv and have been accepted for publication by the journal Astronomy & Astrophysics.
Asteroid 2024 PT5 was first spotted in August, and became entangled with Earth’s gravity in September.
It emerged from the Arjuna asteroid belt, a group of asteroids that orbits the sun at an average distance of roughly 93 million miles and follows a path similar to Earth’s orbit.
‘Some Arjuna asteroid belt objects can approach Earth at a close range of around 2.8 million miles (4.5 million kilometers) and at a relatively low velocity of less than 2,200 miles per hour (3,540 km per hour),’ Carlos de la Fuente Marcos told Space.com.
‘Asteroid 2024 PT5 will not describe a full orbit around Earth. You may say that if a true satellite is like a customer buying goods inside a store, objects like 2024 PT5 are window shoppers.’
Indeed, NASA has stressed that this asteroid never fully entered our planet’s orbit, which means it was never technically a moon. But it is ‘an interesting object’ worthy of study, the agency stated.
To be considered a mini-moon, an asteroid must come within 2.8 million miles of Earth and approach at a relatively slow speed of roughly 2,200 mph, according to Carlos de la Fuente Marcos.
The space rock followed a horseshoe-shaped path around Earth for about two months, giving astronomers like the de la Fuente brothers ample time to study this mini moon.
It’s currently located more than two million miles away from our planet and will begin gradually moving further away today.
Asteroid 2024 PT5 will make another approach to Earth in January, coming as close as 1.1 million miles from out planet. After that point, it will zoom back out into the cosmos and won’t return again until 2055.
‘I won’t really be sad to see 2024 PT5 go; mini-moons come and go as they wish. I am just waiting for the next one,’ Carlos de la Fuente Marcos told Space.com.
‘That wait will not be long; the next capture will probably happen within the next few months. The ongoing Near Earth Object surveys are now sensitive enough to pick up these objects on a regular basis.’
