This is the last time we’ll have a ‘mini-moon’ for 31 years
Our planet is about to gain a second ‘mini-moon’ tonight (29 September), which will remain for a few months.
This object is part of the Arjuna asteroid belt, which, in space terms, is relatively close to Earth, sitting just 2.8 million miles (4.5 million kilometers) away.
Named 2024 PT5, it contributes to the group of asteroids and comets that are being monitored by leading astronomers, including those at the NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS).
Although it will be captured by Earth’s orbit and earn the title of a ‘mini-moon,’ the space rock won’t complete a full orbit around our planet.
What is a ‘mini-moon’?
A ‘mini-moon’ can be described as a ‘temporarily captured object.’ The modestly sized 2024 PT5, with a diameter of approximately 11 meters (about the size of a London bus), will remain in Earth’s orbit for a few months before continuing its journey through the solar system.
However, it will not make a complete orbit. Instead, it will follow a horseshoe-shaped path around Earth, beginning on 29 September and lasting until 25 November. After leaving our planet’s orbit, it will return to a heliocentric orbit, meaning it will orbit the Sun, just like Earth does.
This will be the last time we see the space rock for a while, as it won’t come back into Earth’s orbit until 2055.
How can I see the mini-moon?
Unfortunately, unless you’re a professional, it’s unlikely you’ll be able to see it. The event won’t be visible to the naked eye, binoculars, or even a consumer-grade telescope. The mini-moon will have a magnitude of 22, which is extremely low on the -10 to +20 scale, meaning it will be far too faint to observe.
Even professional equipment may struggle, as some observatories have shared with The Sun that even advanced telescopes could find it difficult to detect 2024 PT5.
Who discovered the new mini-moon?
The ATLAS telescope first spotted the Arjuna asteroid on 7 August in South Africa. This rock is classified as a near-Earth asteroid (NEA).
Arjuna asteroids follow an orbital path around the Sun that stretches a bit further into the Solar System than Earth’s orbit, although some do come close to the Earth-Moon system.
Have there been other mini-moons?
Yes, there have been other mini-moons. Earth has captured and pulled NEAs into its orbit several times before.
In February 2020, an object called 2023 CD3 was found to have been orbiting Earth for a few years before leaving our orbit the following month.
In 2016, an object known as 2016 HO3, with a diameter of 40-100 meters, did not technically orbit Earth, so it wasn’t classified as a moon. However, it moved in sync with Earth, making it appear as if it was orbiting the planet when in reality, it was orbiting the Sun.
Featured Image Credit: NASA/Internet
