3I/ATLAS Interstellar Visitor Might Be Using the Sun for Gravitational Maneuver

On October 29, the unique interstellar object 3I/ATLAS, discovered only four months earlier, approached the Sun. Scientists and the public alike are watching closely. Ever since Harvard astrophysicist Avi Loeb suggested that 3I/ATLAS might be an alien spacecraft, the object has become a subject of fascination and controversy. Loeb suspects the body may have an artificial origin and could even be preparing for braking maneuvers or the release of reconnaissance probes.

Photo: NASA, ESA by David Jewitt (UCLA), oseph DePasquale (STScI), https://creativecommons.org/licenses/by-sa/3.0/

3I/ATLAS Comet

3I/ATLAS and Its Unusual Solar Encounter

Discovered on July 1 through NASA’s telescope network, 3I/ATLAS entered the Solar System several months ago and reached its closest point to the Sun on October 29. Most experts classify it as an interstellar comet. Loeb, however, argues that artificial origin cannot be ruled out.

Loeb, once head of Harvard University’s Department of Astronomy, now leads the Galileo Project and directs both the Black Hole Initiative and the Institute for Theory and Computation at the Harvard–Smithsonian Center for Astrophysics. Though his reputation has been colored by his flair for bold public statements, Loeb continues to publish serious academic work, where his tone is far more restrained than in interviews with outlets like the Daily Mail.

According to Loeb, 3I/ATLAS exhibits numerous unusual properties that set it apart from ordinary comets. The current period, he believes, will reveal whether the object is natural or artificial. It is now perfectly positioned for braking or other actions that could betray its true nature.

“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.” — Avi Loeb, astrophysicist

The Perihelion Test and the Engine Hypothesis

Perihelion, the object’s closest point to the Sun, is a decisive test. If 3I/ATLAS is a natural comet, the heat—reaching 770 watts per square meter—could destroy it. But if the object is artificial, as hinted by its high nickel-to-iron ratio, it might instead perform maneuvers or launch mini-probes. Signs such as artificial luminosity or excess engine heat would further support this theory.

According to Loeb, recent observations indicate that 3I/ATLAS has activated an engine for deceleration. The object is no longer visible from Earth, yet solar observatories continue tracking its behavior. American astronomers Zhichen Zhang and Karl Battams reported a sharp increase in brightness, accompanied by a shift in color—from red to blue. Loeb argues that such spectral change cannot occur naturally. Even the researchers admit they cannot explain it.

In an analysis published on Medium, Loeb noted that 3I/ATLAS brightens much faster than typical Oort Cloud comets. Its color shift might mean that the object’s temperature has surpassed that of the Sun itself.

“The blue glow at perihelion should be added as the ninth anomaly of this strange interstellar visitor. Could it be using a power source hotter than the Sun?” — Avi Loeb, astrophysicist

Nine Anomalies and the “Wow!” Signal Connection

Loeb assigns 3I/ATLAS a score of four on a hypothetical scale where zero indicates a natural object and ten an unquestionably artificial one. He lists nine anomalies, including a trajectory aligned within five degrees of the Solar System’s plane and an “anti-tail”—a jet of particles pointing toward the Sun. While most comets exhibit this as an optical illusion, Loeb believes it reflects real material flow, perhaps the braking thrust of an engine.

“Such a phenomenon would be a technosignature—a sign of controlled maneuvering, possibly to enter a stable orbit between Mars and Jupiter.” — Avi Loeb

Loeb also points out that 3I/ATLAS moves faster than expected and passes unusually close to three planets. At perihelion, it becomes invisible from Earth—an improbable coincidence. Chemically, it contains far more nickel than iron and very little water—just four percent—whereas most comets are water-rich.

Even more intriguingly, 3I/ATLAS entered the Solar System from the same region that once produced the famous “Wow!” radio signal, detected in 1977 during the SETI program’s search for extraterrestrial intelligence. Though never proven artificial, the coincidence adds to the mystery. According to Loeb, the odds of all these anomalies appearing together are one in ten quadrillion—virtually impossible by chance.

Between Science and Speculation

Most experts remain skeptical of Loeb’s bold interpretation, and he himself urges caution, noting that a natural explanation remains far more likely. Still, he argues that vigilance is essential:

“We must gather as much data as possible to determine the nature of this anomalous object. If we discover alien technology, the consequences would be immense. Our largest rocket, Starship, is a hundred times smaller than 3I/ATLAS—if it’s a technological craft, its makers are far ahead of us.” — Avi Loeb

A Career of Cosmic Controversies

Loeb’s career has long been entwined with the search for technosignatures—clues of artificial structures or activity in space. In 2012, he proposed looking for traces of alien megacities on exoplanets. Five years later, he suggested that mysterious fast radio bursts might be signals from extraterrestrial civilizations.

His fascination with interstellar visitors began in 2018 with ‘Oumuamua—the first such object detected by humans. Loeb argued it could be an alien probe, though its swift departure made proof impossible. Another controversy followed his study of meteorite IM1, which fell to Earth in 2014. Intrigued by its high speed, Loeb theorized it might also be of artificial origin. He led an expedition off Papua New Guinea, retrieving metallic spherules from the ocean floor, which he believed were fragments of alien technology.

The mission sparked a diplomatic dispute when local authorities accused him of removing materials without permission.

“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?” — George Polon, Deputy Head of Manus Province, Papua New Guinea

When professional seismologists re-examined the data, Loeb’s theory collapsed. Researcher Benjamin Fernando found that the supposed meteor explosion was in fact vibrations from passing trucks near the monitoring station. Despite such setbacks, Loeb remains undeterred in his quest to find evidence that humanity is not alone in the universe.