Elon Musk Issues Warning About ‘Potentially Hostile Alien Threat’ That Could ‘Kill Most Of Human Life’

The object, officially designated 3I/ATLAS, was first spotted on 1 July by a NASA-funded survey telescope in Chile operated by the Asteroid Terrestrial-impact Last Alert System, or ATLAS. Astronomers quickly realised it was travelling on a hyperbolic path that means it is not bound to the Sun’s gravity and is instead an interstellar visitor, only the third such object ever confirmed after ʻOumuamua in 2017 and Borisov in 2019.

During a recent appearance on the Joe Rogan Experience podcast, Musk was asked about claims from some scientists and commentators that 3I/ATLAS might be more than just an unusually large comet. While emphasising that he believes there are natural explanations for its behaviour, the SpaceX chief executive conceded that “it could be alien, I don’t know,” before outlining what he said would happen if a body of that size ever hit the planet. In remarks later widely shared on social media and reported by multiple outlets, Musk said an impact would “obliterate a continent” and “probably kill most of human life,” stressing that this was a hypothetical scenario rather than a prediction.

Scientists estimate that 3I/ATLAS has a nucleus several kilometres wide and is travelling through the solar system at tens of kilometres per second. Although that is too small to rival the asteroid impact that is believed to have wiped out the dinosaurs, Musk argued that the energy released by a collision would still be catastrophic on a regional or even hemispheric scale. He pointed to the fact that many nickel-rich deposits on Earth are thought to be remnants of ancient impacts, saying those events would have “obliterated” anything living at the site.

The billionaire’s comments came as speculation around 3I/ATLAS has grown, fuelled in part by Harvard astrophysicist Avi Loeb, who has suggested in papers and blog posts that the object might, in an extreme scenario, be an example of extraterrestrial technology. Loeb and colleagues have argued that certain reported anomalies, including what they describe as unusual brightening, colour changes and hints of non-gravitational acceleration, could indicate an artificial origin, though they also acknowledge that a natural explanation is more likely.

In earlier writings about 3I/ATLAS, Loeb described the possibility that the object could represent a “potentially hostile” system, speculating that a technologically advanced civilisation might use interstellar probes to plant surveillance devices around planets such as Earth. He suggested that if such a probe existed and carried weaponry or could direct impactors, “the consequences… could potentially be dire for humanity,” while also stressing that this remained a speculative scenario that required testing and that the most probable outcome was that 3I/ATLAS would prove to be a natural comet.

Those ideas have divided opinion among astronomers. Many researchers argue that the available data are consistent with 3I/ATLAS being a largely conventional comet composed of ice, rock and dust, ejected from another star system billions of years ago and now passing through the inner solar system on a one-off visit. The comet is not expected to come closer to Earth than about 170 million miles when it makes its nearest approach in December, a distance that NASA officials have repeatedly said means there is no realistic impact threat on the current trajectory.

Nevertheless, the object has displayed several features that have intrigued observers. Images from major observatories show a pronounced tail and what some have described as an “anti-tail” that appears to point towards the Sun, an effect that can arise in comets when dust particles spread along the orbit rather than streaming directly away under the pressure of sunlight. Astronomers using the European Space Agency’s ExoMars Trace Gas Orbiter have also helped refine the comet’s path by an order of magnitude, allowing much more precise forecasts of its position as it departs the solar system.

A separate controversy has focused on the object’s brightness and colour near its closest approach to the Sun. Loeb has argued that reports of 3I/ATLAS appearing unusually blue at perihelion, along with suggestions of non-gravitational accelerations, could in principle be consistent with some form of propulsion system or artificial illumination. He has floated the idea that what looks like cometary outgassing could instead be exhaust from a nuclear-powered engine. Other astronomers say standard physics can fully explain the observations, citing outgassing of volatile ices such as carbon dioxide and water as the source of the measured forces and light.

Against this backdrop, Musk’s remarks have given the discussion a far broader public profile. On the podcast, host Joe Rogan raised interpretations that 3I/ATLAS might be an “alien spaceship,” reading from online posts that cited Loeb’s work. Musk responded that while he did not rule out the possibility of extraterrestrial life in the universe, he viewed most such claims with caution and believed there were many natural bodies rich in metals like nickel that could account for the observations. Only after Rogan pressed him on the consequences of a hypothetical collision did Musk describe the scenario in which “most of human life” could be lost.

His comments have resonated strongly among space-focused online communities, where videos and clips from the interview have been widely shared. Some social media users have interpreted his words as a call for more active planetary defence measures, arguing that the potential damage from a large interstellar impact, however remote its odds, justifies investment in detection and mitigation technologies. Others have criticised what they see as alarmist rhetoric about a body that, according to official space-agency assessments, poses no credible threat on its current path.

Outside the realm of speculation, scientists continue to treat 3I/ATLAS primarily as a rare opportunity to study material formed around another star. Observations indicate that the comet is rich in carbon dioxide, suggesting it condensed in the frigid outer regions of its original planetary system before being ejected into interstellar space, where it may have travelled for billions of years. Studies of its composition and structure could shed light on how common such comets are and how they contribute to the exchange of material between star systems.

The comet has already been observed by ground-based telescopes, the Hubble Space Telescope and spacecraft orbiting Mars. ESA’s Trace Gas Orbiter and Mars Express have tracked it during a close pass by the Red Planet, giving astronomers a rare triangulated view that helps pin down its trajectory more accurately than is possible from Earth alone. NASA’s Mars Reconnaissance Orbiter has captured high-resolution images of the nucleus that are expected to be released in full, offering further clues about its make-up and whether it behaves like other comets studied in the past.

Meanwhile, NASA officials have tried to tamp down speculation that 3I/ATLAS represents any immediate danger. In recent comments reported by UK media, the agency’s acting administrator Sean Duffy said the comet contains “no aliens” and poses “no threat to life here on Earth,” reiterating that its projected fly-by distance is hundreds of millions of kilometres.

Even Loeb, whose writings have helped fuel much of the public fascination with the object, has urged readers to treat the alien-craft idea as an intriguing but unlikely hypothesis. In one paper he described his scenario as “remarkable” and “testable,” but acknowledged that “by far, the most likely outcome” is that 3I/ATLAS will turn out to be a completely natural interstellar comet.

For Musk, the episode has provided another platform to argue that humanity should take planetary threats seriously, whether from natural objects or potential technological risks. On Rogan’s programme he linked the discussion of 3I/ATLAS to wider concerns about how vulnerable civilisation would be to any large impact in the absence of robust deflection systems. He suggested that even if, as NASA maintains, the current visitor is not on a collision course, the solar system almost certainly contains other objects whose paths have yet to be discovered or fully understood.

As 3I/ATLAS continues its journey, astronomers say the coming months will bring more data and a clearer picture of its behaviour. For now, the consensus among experts is that the object is an unusual but natural comet that will pass safely by before heading back into interstellar space. Musk’s warning, and the more dramatic scenarios circulating online, are framed as thought experiments rather than forecasts. Yet the intense global interest in this distant body underlines how the discovery of a single object, travelling on a lonely trajectory from another star system, can reignite age-old questions about humanity’s place in the universe and the risks that may exist beyond Earth’s atmosphere.