AN INTERSTELLAR space rock zooming through our solar system may be the oldest comet ever seen by humans, according to researchers.
The mysterious cosmic object was discovered last week, and is believed to have travelled from interstellar space.
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Now researchers say the comet could be older than our solar system by more than three billion years.
That would make the rock a whopping 7.6billion years old, University of Oxford astronomer Matthew Hopkins told the Royal Astronomical Society’s National Astronomy Meeting in Durham.
The ancient hunk of debris, named 3I/ATLAS, is covered in water-based ice – which has given it a “fuzzy” appearance through telescopes.
The celestial visitor is only the third interstellar object on record to grace our solar system, and is also likely the largest yet detected.
It follows the rare visits from the famous 1I/ʻOumuamua asteroid in 2017 and 2I/Borisov in 2019.
Unlike the previous two interstellar objects to enter our solar system, 3I/ATLAS appears to be travelling on a steep path through the galaxy.
Its current trajectory suggests it originated from the Milky Way’s ‘thick disk’ – a field of ancient stars.
No comet from that region has ever graced Earth with a flyby, according to astronomers.
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“All non-interstellar comets such as Halley’s comet formed with our solar system, so are up to 4.5billion years old,” said Hopkins.
“But interstellar visitors have the potential to be far older, and of those known about so far our statistical method suggests that 3I/ATLAS is very likely to be the oldest comet we have ever seen.”
The comet was first spotted on 1 July by the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Río Hurtado, Chile.
But ESO’s Very Large Telescope (VLT) has obtained new images of the comet and its path, shown as a dotted line.
Professor Chris Lintott, co-author of the study and presenter of the BBC’s The Sky at Night, added: “This is an object from a part of the galaxy we’ve never seen up close before.
“We think there’s a two-thirds chance this comet is older than the solar system, and that it’s been drifting through interstellar space ever since.”
What’s the difference between an asteroid, meteor and comet?
Here’s what you need to know, according to Nasa…
- 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 vaporizing)
The lonesome space rock, believed to be leftover material of the early solar system, has been on quite the journey over its lifetime.
As it approaches our Sun, the rock will heat up and release gas and dust from the heart of the comet.
It’s this that gives comet’s their fuzzy glow and tail.
Peter Veres, an astronomer with the International Astronomical Union’s Minor Planet Centre, said last week: “It looks kind of fuzzy… It seems that there is some gas around it, and I think one or two telescopes reported a very short tail.”
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While astronomers are still refining their calculations, the object appears to be zooming more than 60 kilometers (37 miles) a second.
The comet poses no threat to Earth, said Richard Moissl, head of planetary defense at the European Space Agency (ESA).
It’s closest approach of Earth, which is projected to occur in late October, will see it pass “just inside the orbit of Mars,” according to Moissl.
It will pass our blue dot no closer than 240 million kilometres – over 1.5 times the distance between Earth and the Sun.
While it will be quite far away, it might still be a once in a lifetime spot for stargazers.
Researchers reckon 3I/ATLAS should be visible through a reasonably-sized amateur telescope sometime in late 2025 and early 2026.
An exact date – or days – will be announced closer to the time.
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All you need to know about planets in our solar system
Our solar system is made up of nine planets with Earth the third closest to the Sun. But each planet has its own quirks, so find out more about them all…
- How old is Earth? Plus other facts on our planet
- How many moons does Mercury have?
- What colour is Venus?
- How far away is Mars to Earth? And other facts on the red planet
- How big is Jupiter?
- How many moons does Saturn have?
- Does Uranus have rings?
- How many moons does Neptune have?
- How big is Pluto?
- How hot is the Sun?
