Are materials from 3I/ATLAS on their way towards Earth? Avi Loeb shares his thoughts
While 3I/ATLAS did make its closest approach to Earth on December 19, 2025, it was still around 167 million miles away at the time. That's about twice the average distance between Earth and the Sun. But in case you are still wondering if it was close enough to send some of its material our way, Harvard astronomer Avi Loeb has got you covered. He doesn't think it's a real possibility. And we might want to thank your stars that it's not.
That's because the gas plume that surrounds 3I/ATLAS contains cyanide and hydrogen cyanide, which, as Loeb reminded in his blog on Medium, was used as a chemical weapon during World War I. However, Loeb claims that the mass loss rate measured by the James Webb Telescope (reported in the study here) indicates that the gas would be swept away by the solar wind within just a few million kilometers of the comet.
Loeb said that dust particles smaller than a micrometer would be swept by the solar radiation pressure much faster than by the solar wind. The solar wind, however, would not affect solid particles or objects bigger than a millimeter. That's because their smaller cross-section per unit mass allows them to continue on their path without too much interference from the solar wind. That being said, despite the failure of solar winds, these particles will burn up in the Earth’s atmosphere before hitting the ground. Then again, Loeb highlighted that this was only possible if the material shed was “much smaller than a meter.”
While 3I/ATLAS might have also released objects bigger than a meter, Loeb thinks there is a negligible chance that any of them would hit Earth. That's because the mass loss rate of the comet suggests that there are fewer than a million such objects, which is too low to cause any alarm or interest. On top of that, the fact that they originated at a distance larger than that between Earth and the Sun means that they wouldn't get any closer than ten times the Earth's radius.
“This, of course, is under the assumption that the released objects cannot maneuver by technological propulsion,” Loeb warned at the end, referring to his controversial argument that there is a chance, no matter how small, that 3I/ATLAS could be a technological object—a position that drew considerable flak from the scientific community.
However, despite flagging certain anomalies in the interstellar comet to support the “alien technology” theory, Loeb’s final stand is clear. He wrote in his blog that he always stood with the theory that “3I/ATLAS is most likely a natural object.” He disapproved of the media reporting his stand as “news,” likely because his constant association with the alien theory drowned out his position. He clarified that his view was to always be open to the technological aspect of the object and not to discard the possibility entirely, all of which influenced his “Loeb scale.”
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