Mercury in retrograde, Jupiter returning, or even a super blue moon. People can place great importance on what’s happening in the skies above our heads, but I have no idea how we should interpret this. Like something ripped out of a sci-fi novel, the Earth is about to get a new moon.
At the end of this week (Sunday, September 29), the Earth’s gravitational pull will trap an asteroid in its orbit. But unlike our current moon (which has been orbiting Earth for 4 billion years), this ‘mini-moon’ won’t be hanging around for long – it’s due to return to its natural asteroid belt home on November 25.
What’s happening!?
On August 7, 2024, scientists discovered the asteroid 2024 PT5 and noticed its peculiar behaviour. Belonging to the Arjuna asteroid belt, described as a “near-Earth object”, it follows a very similar orbit around the sun to our planet – with asteroids in the Arjuna belt approaching Earth as close as 2.8 million miles away.
Combine this with the fact that 2024 PT5 is predicted to be travelling particularly slowly for an asteroid – around 2,200mph – the asteroid will slip into the Earth’s orbit for the next two months. It won’t follow a full orbit around Earth, however, and will return to the Arjuna asteroid belt at the end of November.
“You may say that if a true satellite is like a customer buying goods inside a store, said objects like 2024 PT5 are window shoppers,” said Carlos de la Fuente Marcos, lead researcher and professor at Universidad Complutense de Madrid, speaking to Space.com.
How common is this?
As the study points out, “Earth can regularly capture asteroids from the Near-Earth object (NEO) population and pull them into orbit, making them mini-moons.” Recent examples include 2006 RH120 which remained gravitationally bound to Earth from July 2006 to July 2007; and 2022 NX1 – a short-lived mini-moon of Earth in 1981, 2022, and will return in 2051. But there are countless others.
How can I see Earth’s new ‘mini-moon’?
It’s unlikely that any of us will get to see it. This ‘mini-moon’ is far too small for amateur astronomers – even with telescopes and binoculars. However, the asteroid will be visible to many professional astronomers. “A telescope with a diameter of at least 30 inches plus a CCD or CMOS detector are needed to observe this object,” said Carlos.