On October 29, the interstellar object 3I/ATLAS, which was discovered just four months prior, made its closest approach to the Sun. This event has drawn significant attention from both scientists and the public. The object”s intrigue escalated after Avi Loeb, an astrophysicist from Harvard University, proposed that 3I/ATLAS could potentially be an alien spacecraft. Loeb has posited that the object may have an artificial origin and might be preparing to execute braking maneuvers or deploy reconnaissance probes.
Identified on July 1 through NASA“s telescope network, 3I/ATLAS entered the Solar System several months ago and reached its perihelion on October 29. While most experts categorize it as an interstellar comet, Loeb argues that the possibility of an artificial origin should not be dismissed.
Loeb, who previously led Harvard”s Department of Astronomy and now heads the Galileo Project while also directing the Black Hole Initiative and the Institute for Theory and Computation at the Harvard–Smithsonian Center for Astrophysics, has a reputation for making bold statements. Nonetheless, he continues to contribute serious academic research, where his tone is notably more reserved than in interviews.
Loeb claims that 3I/ATLAS displays several unusual characteristics that distinguish it from typical comets. He believes this period will determine its true nature—whether it is natural or artificial. “If my suspicions are correct and 3I/ATLAS is indeed an alien craft, it may use the Sun”s gravity to slow down before approaching Earth. While hidden behind the Sun, it might even deploy miniature reconnaissance probes,” he stated.
The Perihelion Test and Engine Hypothesis
The perihelion, or the closest point of the object to the Sun, serves as a critical test for understanding its nature. If 3I/ATLAS is a natural comet, the extreme heat—reaching 770 watts per square meter—could destroy it. Conversely, if it is artificial, as suggested by its unusual nickel-to-iron ratio, it might perform maneuvers or deploy mini-probes. Indicators such as artificial brightness or excess heat could further support this hypothesis.
Recent observations have suggested that 3I/ATLAS may have activated an engine for deceleration. Although it has become invisible from Earth, solar observatories are still monitoring its activity. American astronomers Zhichen Zhang and Karl Battams reported a significant increase in brightness and a shift in color from red to blue. Loeb contends that such a spectral change cannot occur naturally, a view that even the researchers acknowledge they cannot explain. In an analysis published on Medium, Loeb noted that 3I/ATLAS brightens at a much faster rate than typical Oort Cloud comets, and its color shift may indicate that its temperature has exceeded that of the Sun.
“The blue glow at perihelion should be considered the ninth anomaly of this peculiar interstellar visitor. Could it be utilizing a power source that is hotter than the Sun?” Loeb questioned.
Nine Anomalies and Intriguing Connections
Loeb assigns a score of four to 3I/ATLAS on a hypothetical scale where zero represents a natural object and ten indicates an unmistakably artificial one. He has identified nine anomalies, including a trajectory closely aligned with the Solar System”s plane and the presence of an “anti-tail,” which is a jet of particles flowing toward the Sun. While this is typically seen as an optical illusion, Loeb believes it may reflect genuine material flow, possibly indicating engine thrust.
Loeb also highlights that 3I/ATLAS is moving more rapidly than anticipated and passes unusually close to three planets. At its perihelion, it becomes invisible from Earth, a striking coincidence. Chemically, the object contains significantly more nickel than iron, with only four percent water content, unlike most comets, which are water-rich. Even more compelling is the fact that 3I/ATLAS entered the Solar System from the same region that generated the famous “Wow!” signal in 1977, detected during the search for extraterrestrial intelligence. Although the signal”s artificial nature has never been confirmed, its coincidence adds to the enigma surrounding 3I/ATLAS.
Loeb calculates that the odds of all these anomalies occurring together are one in ten quadrillion, suggesting that such a combination is virtually impossible by chance.
Despite the skepticism from many experts regarding Loeb”s interpretations, he advocates for caution, acknowledging that a natural explanation is still more probable. However, he emphasizes the need for thorough data collection to ascertain the nature of this anomalous object. “If we discover alien technology, the implications would be monumental. Our largest rocket, Starship, is a hundred times smaller than 3I/ATLAS—if it is indeed a technological craft, its creators are far more advanced than we are,” Loeb concluded.
Loeb”s career has been marked by a focus on the search for technosignatures, indicators of artificial structures or activities in space. In 2012, he proposed investigating signs of alien megacities on exoplanets. Five years later, he suggested that mysterious fast radio bursts might be signals from extraterrestrial civilizations. His interest in interstellar visitors began in 2018 with “Oumuamua, the first such object detected. Loeb hypothesized it could have been an alien probe, although its rapid departure precluded confirmation.
Another controversy surrounded his study of the meteorite IM1, which fell to Earth in 2014. Intrigued by its high velocity, Loeb speculated it might also originate from an artificial source. He led an expedition off Papua New Guinea, recovering metallic spherules from the ocean floor, which he believed to be remnants of alien technology. This mission sparked a diplomatic dispute when local authorities accused him of extracting materials without consent. “They came here, no one knew, and now they”re gone. What did they find? Are those findings valuable? Do we have rights to these objects?” questioned George Polon, Deputy Head of Manus Province, Papua New Guinea.
When professional seismologists re-evaluated the data, Loeb”s theory was discredited. Researcher Benjamin Fernando determined that the supposed meteor explosion was actually vibrations from passing trucks near the monitoring station. Despite such challenges, Loeb remains steadfast in his pursuit of evidence that humanity is not alone in the cosmos.
