Probing claim that interstellar object is ‘most likely’ an alien ship heading towards Earth

Rumors of an incoming alien attack invaded some social media feeds in late July 2025 after the New York Post published an article about a potential “alien probe.”

While the article only said the object in question “could” be an alien probe, posts on social media described the situation with far more alarm. 

For example, an Instagram post (archived) with 15,000 likes warned of an “intergalactic object” that was “most likely” an alien ship heading toward Earth. A Facebook post (archived) with 12,000 reactions sarcastically said an astrophysicist was “certain” the object was an alien ship, a claim many in the comments appeared to take at face value. An X post (archived) viewed more than 1.4 million times claimed a hostile alien ship was headed for Earth within the next three months. A TikTok video (archived) claimed that scientists said a “dangerous alien ship” was heading toward Earth and would arrive within the year.

A Snopes reader asked us to fact-check the claim.

The claim was false. Scientists did not warn that an “intergalactic” object was “most likely” or “certainly” an alien ship heading toward Earth. The overwhelming scientific consensus was that the object was likely an interstellar comet. A few scientists published a paper analyzing a theoretical argument that it could be an alien ship, but even the paper’s authors believed it to most likely be a comet.

On July 1, 2025, scientists discovered 3I/ATLAS, an interstellar object both NASA and the European Space Agency have called a comet. (An “interstellar” object is one that travels between star systems, hundreds of billions of which can be found in the Milky Way galaxy alone. An “intergalactic” object travels between galaxies, and therefore such an object by definition must originate outside the Milky Way.)

The idea that the object was an alien ship came from misunderstandings and misrepresentations of a paper titled “Is the Interstellar Object 3I/ATLAS Alien Technology?” by Harvard astrophysicist Abraham “Avi” Loeb and two researchers from the United Kingdom. But despite the title of the paper, which had not been peer-reviewed by the time it spread on social media, the paper’s authors did not believe the answer to the question in the title was “yes.”

“By far the most likely outcome will be that 3I/ATLAS is a completely natural interstellar object, probably a comet, and the authors await the astronomical data to support this likely origin,” wrote the scientists in the paper’s conclusion.

In the paper’s introduction, the authors wrote that one of the reasons for analyzing the hypothesis that the comet could actually be alien technology was that “The hypothesis is an interesting exercise in its own right, and is fun to pursue, irrespective of its likely validity.”

The scientists wrote that if the object was alien technology, its intentions would be either harmless, malicious or somewhere in between. Because humanity would need to do nothing if an alien craft had harmless intentions, according to the paper’s authors, the possibility that it could be malicious would be of more concern. Thus, the paper assumed the object would be dangerous to humans if it were an alien ship.

After its discovery of the object, NASA said on an informational webpage that 3I/ATLAS would “remain far away” and pose “no threat to Earth.”

The hypothesis that 3I/ATLAS could reach Earth by November wasn’t based on the current projected path of the object. Instead, the authors of the paper estimated the arrival time based on maneuvers a theoretical alien ship could make using the gravity of the Sun or Jupiter to launch such a ship in the direction of Earth.

This was not the first time that Loeb, the Harvard astrophysicist, tried to encourage other scientists to consider the unlikely hypothesis that an interstellar object could be of artificial origin. In 2017, after the discovery of the first recorded interstellar object to enter the solar system, Loeb told The Guardian, “Most likely it is of natural origin, but because it is so peculiar, we would like to check if it has any sign of artificial origin, such as radio emissions.”