Interstellar object mystery may have been solved as scientists share 'excitement'

A mysterious interstellar object discovered by astronomers may be the oldest comet seen to date, scientists have said. Matthew Hopkins, an astronomer at the University of Oxford, said there was a lot of excitement about the object, called 3I/Atlas.

Experts from the university have suggested it may be three billion years older than our solar system. Mr Hopkins said the object could be over seven billion years old. The object, said to be the size of Manhattan, was spotted 670 million kilometres from the sun on July 1 by the NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS) survey telescope in Rio Hurtado, Chile.

Astronomers have since then been trying to find out more about it and its path. Comet 3I/ATLAS poses no threat to Earth.

The closest it will approach our planet is about 1.8 astronomical units, which is about 170 million miles or 270 million kilometers.

Mr Hopkins told the BBC he believes its origins lay in the Milky Way's "thick disk" group of stars, which orbit areas over and above where the Sun and majority of stars can be found.

Professor Chris Lintott, co-author of a study about the discovery, said the object is from a part of the galaxy never before seen up close.

He said: "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."

It should be possible for star-gazers to see 3I/Atlas using amateur telescopes later this year. NASA said it should be visible in September and December.

Experts believe the object formed around an old star. Much of 3I/Atlas is made up of water and ice. Blazes of dust and vapour are expected to appear as a result of its nearing the Sun, creating a glowing tail.

Comets are known as cosmic snowballs comprised of gases, rock and dust. When nearing the sun they heat up and spew dust and gas into a giant glowing head.

The dust and gases form a tail which can stretch for millions of miles, according to NASA. Comet 3I/ATLAS is the third known object from outside our solar system to be discovered.

The first known interstellar object, named Oumuamua, was spotted in 2017. The second, 2I/Borisov, was discovered in 2019.

Comets are usually named after their discoverers so in the case of 3I/Atlas, the ATLAS survey team. The letter "I" is for "interstellar", which means the object is from outside our solar system. It’s the third known interstellar object, hence the number in its name.