Professor Brian Cox has moved to shut down growing online theories claiming that an interstellar object, 3I/ATLAS, could be an alien spacecraft approaching Earth. The astrophysicist, known for his accessible explanations of complex science, urged the public to rely on verified research rather than “drivel” circulating on social media. 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.
A rare visitor from beyond the solar system
3I/ATLAS was first detected on 1 July by NASA’s Asteroid Terrestrial-impact Last Alert System (ATLAS), a global early-warning network run by the University of Hawaii and funded by NASA. The network operates telescopes in the United States, Chile, and South Africa, designed to identify objects that could pose a threat to Earth. The discovery of 3I/ATLAS marked only the third known interstellar object ever observed entering our solar system. Measuring roughly the size of New York, the comet’s path and behaviour immediately drew the attention of scientists. NASA classified it as interstellar based on the distinctive shape of its orbital path, confirming that it did not originate within our solar system. The agency also stated unequivocally that it “poses no threat to Earth and will remain far away”, passing no closer than 170 million miles from our planet. Astronomers noted several unusual features, including changes in colour and the emission of strange jets — that set 3I/ATLAS apart from typical comets. Its hyperbolic orbit means it will pass through our system once before heading permanently back into deep space. The trajectory is aligned closely with the orbital planes of Venus, Mars, and Jupiter, though it will not come near Earth. While the object’s unusual activity has sparked intrigue, experts believe it may simply be exhibiting natural cometary outgassing, where volatile materials evaporate under sunlight, creating bursts of gas and dust.
The alien craft theory and its promoters
Despite the scientific explanations, Harvard theoretical physicist Professor Avi Loeb has argued that 3I/ATLAS could be a “technological artefact” created by an intelligent civilisation. In a paper co-authored with Adam Hibberd and Adam Crowl, Loeb wrote:“The hypothesis in question is that [3I/ATLAS] is a technological artefact, and furthermore has active intelligence.” He went on to suggest that “two possibilities follow”:“First, that its intentions are entirely benign and second, they are malign.” Loeb has previously claimed the comet could be “potentially hostile” and may even be “braking thrust” as it approaches Earth, implying that it might be under control. In interviews, he estimated a 30 to 40 per cent chance that 3I/ATLAS is not naturally formed. Ranking it on what he called “the Loeb scale” — where zero represents a normal space rock and ten denotes confirmed artificial origin, he placed 3I/ATLAS at a four. “So that means it’s most likely natural,” he told LADbible, “but nevertheless it’s a very high probability for it being something else, and that’s why we should continue to consider it seriously.” Loeb further described it as a potential “black swan event” — a rare, high-impact occurrence that defies expectation. His claims have divided the scientific community, with most astronomers rejecting the notion of alien involvement. Among the sceptics is astrophysicist Neil deGrasse Tyson, who dismissed the theory outright, saying:“We have good data on our own comets and asteroids and moons and planets…. You want to say aliens are coming? OK, it’s clickbait. Nobody else is saying that about this object but Avi Loeb and his group.”
Brian Cox’s firm rebuttal
Professor Brian Cox, never one to indulge in unsubstantiated speculation, addressed the controversy head-on this week. Writing on X (formerly Twitter), he began:“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.” He went on to offer a poetic but firmly scientific perspective on its 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 directed his followers towards verified data, 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).” Cox’s comments serve as a reminder of his longstanding stance against misinformation, particularly when speculation outpaces evidence. His message is simple: extraordinary claims require extraordinary proof, and 3I/ATLAS is, by all available data, nothing more, or less, than a fascinating natural wanderer from another star system.
