A BUS-SIZED “mini moon” is in the final days of its trip to Earth’s skies – and will soon vanish until 2055.
The holidaying asteroid turned up in Earth’s orbit on September 29 this year.
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It was first spotted on August 7 by a Nasa-funded asteroid alert system.
The space visitor is about 33 feet wide, which might sound scary – but Nasa notes that it “does not pose a hazard to Earth”.
And it’s far smaller than the actual Moon, which is around 11.4 million feet wide.
The “mini moon” – as this type of space phenomenon is known – is officially called Asteroid 2024 PT5.
Mini moons aren’t particularly rare, but they can be very difficult to spot.
“This mini moon is particularly interesting for its size – it’s one of the largest ones. But it’s not a rare event,” said Barbara Castanheira Endl, assistant professor of physics at Baylor University in Texas.
“These objects are very faint and we can only see them by the light they reflect.
“It’s possible that an asteroid of the size of a dishwasher is orbiting our planet at any given time and we don’t even notice it.”
The asteroid is due to leave Earth’s orbit on Monday, November 25 at 4.43pm in the UK – or 11.43am in New York.
It’s believed that the asteroid previously appeared near Earth as a “mini moon” in the 1960s.
And it’s expected to return again in 2055.
That gives you a bit more time to prepare, as it’s extremely difficult to spot the “mini moon” on this trip.
It’s such a small object that you won’t spy it with binoculars, or even entry-level and amateur telescopes.
You’ll need a very large telescope – Baylor University recommends a 30-inch model at the very least.
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The object is believed to hail from the Arjuna asteroid belt.
These “Arjunas” follow Earth-like orbits, typically lasting about a year.
The Asteroid 2024 PT5 is passing Earth at about “nine times” the distance of the Moon, according to Nasa.
“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 (CNEOS) suspect that the object could be a large chunk of rock ejected from the Moon’s surface after an asteroid impact long ago,” Nasa explained.
What’s the difference between an asteroid, meteor and comet?
- Asteroid: An asteroid is a small rocky body that orbits the Sun. Most are found in the asteroid belt (between Mars and Jupiter) but they can be found anywhere (including in a path that can impact Earth)
- Meteoroid: When two asteroids hit each other, the small chunks that break off are called meteoroids
- Meteor: If a meteoroid enters the Earth’s atmosphere, it begins to vapourise and then becomes a meteor. On Earth, it’ll look like a streak of light in the sky, because the rock is burning up
- Meteorite: If a meteoroid doesn’t vapourise completely and survives the trip through Earth’s atmosphere, it can land on the Earth. At that point, it becomes a meteorite
- Comet: Like asteroids, a comet orbits the Sun. However rather than being made mostly of rock, a comet contains lots of ice and gas, which can result in amazing tails forming behind them (thanks to the ice and dust vapourising)
“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.”
The “mini moon” was spotted by the University of Hawaii’s Asteroid Terrestrial-impact Last Alert System (ATLAS), which is funded by Nasa.
But the telescope itself is actually located in Sutherland, South Africa.
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Nasa said the asteroid is due to safely “leave the vicinity of Earth as it continues its orbit around the Sun”.
Even if it did somehow get close to Earth, it would simply burn up, according to Matt Pryal, assistant professor of astronomy at the University of Virginia.
“It’s cool because it gives us a better understanding of near-Earth asteroids, a better understanding of our detection techniques and being able to predict when they’re going to come close to the Earth,” Pryal explained.
“It’s maybe about 30 feet across, which is what people are estimating based on how bright it is.
“It’s going to get about a million miles or so away from the Earth.
“So not closer than the moon, and not something that’s going to be visible to the naked eye.”
He also explained that there are plenty of space objects that are floating around up above Earth.
And most of them are no cause for concern.
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“A good amount of this debris forms the asteroids in the asteroid belt between Mars and Jupiter, primarily, but there are still leftover products throughout the solar system,” Pryal explained.
“There are thousands of near-Earth asteroids that basically orbit at the same distance that the Earth orbits from the sun – this asteroid being an example of one of them.
“The next time it’s going to get gravitationally captured by the Earth is around 2055.
“It’s probably just going to keep happening, never getting really close, never getting closer to the moon, unless something gravitationally moves it one way or another.”
He added: “There are hundreds to thousands of artificial moons that humans put up that are orbiting the Earth and are a lot cooler than this object.
“The International Space Station, when it’s directly over our head in Charlottesville, is physically closer to us than New York City because it’s only about 250 miles away.”