Is 3I/ATLAS an Alien Spacecraft or Just a Comet?
20th Nov. 2025
A mysterious visitor from beyond the Solar System has reignited debate across the scientific community. The object, known as 3I/ATLAS, was first spotted in July 2025 by the ATLAS survey telescope in Chile. Its highly hyperbolic orbit has confirmed that it came from interstellar space. But what exactly it remains contentious.
Some of the most provocative speculation came from Harvard astrophysicist Avi Loeb, who has proposed in his recent journal paper that 3I/ATLAS could in fact be a form of alien technology rather than a conventional comet. Loeb argues that several of the object’s behaviours are “anomalous”. Its trajectory lies unusually close to the plane of the Solar System, and it has reportedly displayed a sunward “anti-tail”. There are also claims of gas jets and nickel-rich emissions. He even raises the possibility that it may be employing a manoeuvre similar to thrust, suggesting a deliberate slowing down near perihelion.
However, some claim that the weight of evidence may favor a more mundane explanation, that 3I/ATLAS is a comet. Observations from the James Webb Space Telescope (JWST) revealed a coma dominated by carbon dioxide, along with water ice, carbon monoxide, and dust. They are all considered the hallmarks of cometary activity. Ultraviolet data from the Swift Observatory further detected hydroxyl radicals, by-products of water sublimation, indicating active outgassing. Meanwhile, Hubble Space Telescope measurements place the nucleus size at under 3 km in radius, consistent with many known comets.
NASA officially remains unpersuaded by the alien hypothesis. Their analyses suggest that despite the object’s unusual speed and trajectory, its structure, mass loss, and behavior closely match what one would expect from a natural, interstellar comet.
In short, while Loeb’s theory has stoked public imagination, most researchers emphasize that extraordinary claims require other collaborative evidence to prove that the 3I/ATLAS is a spacecraft, and not a comet. Till then, it appears to remain firmly in the realm of natural science.
Web Resources on 3I/ATLAS
1. NASA.gov: Comet 3I/ATLAS Image Gallery
2. IFLScience.com: NASA Responds To Claims That Interstellar Object 3I/ATLAS Is An Advanced Alien Spacecraft
3. Guardian.com: Nasa debunks claim about alien-made comet