We have no clue about alien neighbors in our immediate cosmic environment. Rather than have strong opinions on the matter, we better study interstellar objects to find these clues. Perhaps among the interstellar icy-rocks of natural origin, there will also be a technologically-made “tennis ball” thrown by a neighbor.
Even our biggest telescopes cannot detect reflected sunlight from a giant spacecraft, as big as Manhattan Island, that lies beyond 100 times the Earth-Sun separation. Our observatories will trace it only as it gets closer than 10 times the Earth-Sun separation, as was the case with 3I/ATLAS — inferred to be of that size. From an alien base at 1000 times the Earth-Sun separation, spacecraft with the speed of 3I/ATLAS can reach Earth within 80 years. Ignoring the possibility of alien technologies before analyzing the evidence is not a mark of intelligence at our end. We simply do not know what lies in interstellar space and so we must search through new data from the NSF-DOE Rubin Observatory for any anomalous interstellar objects. With that in mind, if 3I/ATLAS will behave in the coming months just like the previous interstellar comet 2I/Borisov did as it approached the Sun, then we will know that 3I/ATLAS is natural in origin.
For genuine scientists: the more data, the better. For influencers and conspiracy theorists on social media: the less data, the better.
In my latest paper with Adam Hibberd and Adam Crowl, I proposed using the Juno spacecraft, currently in orbit around Jupiter, to probe 3I/ATLAS, when it will pass on March 16, 2026 within a distance of 53.6 million kilometers from Jupiter. Congresswoman Anna Paulina Luna, supported this proposal by sending a letter to NASA’s leadership encouraging the use of Juno as a probe of 3I/ATLAS. To my surprise, some scientists were inclined to say bad things about this proposal on social media. As Sir Martin Rees noted on a recent podcast with Michael Shermer: “I would rather pay attention to a first-class science fiction writer than to a second-class scientist.” I wholeheartedly agree with Martin.
But there is a caveat. Science fiction imagines possibilities that violate the laws of physics, which I regard as not viable based on our current scientific knowledge. That still leaves a huge space for innovative technologies that extend well beyond our abilities.
My collaborator, Omer Eldadi, suggested that aliens might use a natural interstellar comet as a decoy to attract our attention when they conduct another operation at a different location near Earth. Given that perspective, it would be interesting to check whether there is an enhanced activity of Unidentified Anomalous Phenomena (UAP) in the Earth’s atmosphere in the aftermath of the closest approach of 3I/ATLAS to the Sun on October 31, 2025. Gladly, the Galileo Project will be monitoring the sky under my leadership with its three observatories — in Massachusetts, Pennsylvania and Nevada — during that period.
An avid reader of my work, Gábor Szóka, proposed that aliens may terraform natural rocks and employ them as spacecraft, deceiving astronomers from identifying their technological nature. He argued that a Stealth Hybrid Asteroid–Spacecraft is a reasonable possibility because “humanity is already planning asteroid mining missions and for a more advanced civilization, this could be a routine and multi-purpose technology — enabling habitable internal space and perhaps efficient storage of propellant within the asteroid. Beyond fuel constraints, cosmic radiation and micro-impacts from space debris pose serious risks to long-range missions. An asteroid hull provides excellent natural shielding […] The object offers inherent stealth: as long as there are no active emissions or artificial reflective surfaces, it appears externally to be just a natural asteroid […] If Earth is a target, trajectory corrections could occur behind multiple celestial bodies, remaining hidden from view — and would only become detectable once the object emerges again from behind its passage behind the Sun.” Given this perspective, we should search for anomalies in interstellar asteroids or comets that may indicate technological manufacturing. Nevertheless, at the end of our analysis, we must abide to the common sense of the Duck Test: “if the interstellar object looks like a comet, moves like a comet, and outgasses like a comet, then it probably is a comet.”
Only one among the tens of podcasters that interviewed me this week noted: “Members of my audience raised the suspicion that the announcement about 3I/ATLAS was meant to distract us from the Jeffrey Epstein files!” I responded that 3I/ATLAS can be observed in the sky by any person who owns a 0.5-meter telescope. It exists in space, moves twice as fast as any human-made rockets, and probably travelled along its path far longer than the 72 years that elapsed since 1953, when Jeffrey Epstein was born. The existence of 3I/ATLAS is a fact about the physical reality that has nothing to do with our terrestrial politics. Other variants of this conspiracy theory discredited my analysis of 3I/ATLAS because of my Jewish or Israeli roots. This led me to realize that the simplest solution to Fermi’s question: “Where is everybody?” is that the aliens do not consider us sufficiently intelligent to be worth their attention. Given these conspiracy theories, I do not blame them.
ABOUT THE AUTHOR
Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.