Comet 3I/ATLAS an alien spacecraft? American physicist Brian Cox breaks silence on Manhattan-sized interstellar visitor

Amid the growing mystery around interstellar comet 3I/ATLAS, American professor Brian Cox has dismissed claims that the cosmic visitor is an 'alien spacecraft', calling such theories 'drivel'. Brian Cox made an appeal to the public to rely only on reliable information rather than conspiracy theories surrounding comet 3I/ATLAS. Cox, known for his accessible explanations of complex science, has responded amid multiple online theories claiming that an interstellar object, 3I/ATLAS, could be an alien spacecraft approaching Earth.

His response comes amid mounting speculation fuelled by Harvard astrophysicist Avi Loeb, who has suggested the object might be an artificial craft rather than a natural comet. “Just to be clear – given recent drivel online – Comet 3I/ATLAS is a comet, made of carbon dioxide and water ices and bits of other stuff. It is entirely natural in origin, its orbit is as expected, and it will whizz around the sun and then disappear off into the galaxy again," Brian Cox said in a post on X, formerly known as Twitter.

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What Brian Cox has said about comet 3I/ATLAS

Brian Cox has offered a firm scientific perspective on interstellar comet 3I/ATLAS's journey through space. “If it ever encounters another inhabited solar system in the far future I hope the living things there are more sensible than us and enjoy it for what it is – a visitor from elsewhere in the galaxy – a pristine lump of rock and ices which formed around a distant, maybe long-dead star billions of years ago and many light years away, just passing through. Isn’t that wonderful enough?”

Cox also shared verified data with followers, sharing links to credible sources and adding: “This is the place you should look if you want detailed, reliable information. These are not yet published in journals and care is still required, but it’s as good a place as any to see fast-developing research in action, and if you have questions you may find answers here.”


He followed with practical guidance for evaluating scientific claims: “A good rule of thumb is to look at the ones that have been submitted to journals (usually noted in the comments).”

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Multiple theories around comet 3I/ATLAS

Despite scientific explanations dismissing alien involvement about comet 3I/ATLAS, Harvard theoretical physicist Avi Loeb has suggested that the object 3I/ATLAS could be a “technological artefact” created by an intelligent civilization. In a paper co-authored with Adam Hibberd and Adam Crowl, Loeb wrote that the object might not only be artificial but could also possess “active intelligence.” He outlined two possibilities — that its intentions are either benign or malign.

Loeb has previously speculated that the comet could be “potentially hostile” and even “braking thrust” as it nears Earth, hinting it might be under control. He estimated a 30–40% chance that 3I/ATLAS is not naturally formed. On his self-devised “Loeb scale,” where zero represents a normal space rock and ten indicates a confirmed artificial origin, he rated the object a four.

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“That means it’s most likely natural,” he told LADbible, “but it’s still a high enough probability that we should take it seriously.” Loeb described it as a possible “black swan event” — a rare, high-impact occurrence that defies expectations.

3I/ATLAS was first detected on 1 July by NASA’s Asteroid Terrestrial-impact Last Alert System (ATLAS) and its discovery marks of 3I/ATLAS marked only the third known interstellar object ever observed entering our solar system. It measures roughly the size of New York and its mysterious path and behaviour immediately drew the attention of scientists.

NASA classified 3I/ATLAS as an interstellar object after identifying the distinctive shape of its orbital path, confirming it did not originate within our solar system. The agency also stated that the object “poses no threat to Earth and will remain far away,” passing no closer than 170 million miles from the planet.

Astronomers have observed several unusual characteristics, including color changes and the emission of strange jets, which makes 3I/ATLAS different from other comets. Its hyperbolic orbit means it will pass through the solar system only once before heading permanently back into deep space. The object’s trajectory aligns closely with the orbital planes of Venus, Mars, and Jupiter, but it will not come near Earth.

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