On July 1, 2025, the ATLAS sky survey spotted only the third known object to enter our solar system from interstellar space. It was named 3I/ATLAS.

Within weeks, Harvard astrophysicist Avi Loeb and two co-authors posted a paper titled “Is the Interstellar Object 3I/ATLAS Alien Technology?” on arXiv, a site for research that hasn’t yet been peer reviewed. The paper lists features the authors call anomalous, including the object’s large apparent size and a path that brings it close to several planets. They argue those traits are at least consistent with a technological object. In later public comments, Loeb suggested it could be on a mission and might release smaller probes. He has also tried to link it to the famous 1977 “Wow!” radio signal.

No proof has been shown that the object is artificial, and the authors themselves say they don’t necessarily believe their own hypothesis. Mainstream astronomers have been firmly skeptical. Observations from Hubble, the James Webb Space Telescope and other instruments have been read as showing an ordinary, if very old, natural comet. NASA has said it poses no threat.

Loeb made a similar argument about the interstellar object ‘Oumuamua in 2017. He leads the Galileo Project, which searches for signs of alien technology.