Harvard Scientist Suggests Interstellar Object Could Be Alien Spacecraft

A strange Interstellar object speeding through the solar system has sparked debate among scientists after a Harvard astrophysicist suggested it may not be a natural comet but something far more unusual — potentially an alien spacecraft.

The object, officially named 3I/ATLAS, was detected on July 1. Researchers have been monitoring it closely because of its unusual orbit and size. Unlike most comets, 3I/ATLAS is traveling in the opposite direction of the planets and aligns almost perfectly with the same plane in which Earth and other inner planets orbit. According to Harvard scientist Avi Loeb, the chances of this alignment happening naturally are extremely low, which he estimates at just 0.2 percent.

Unidentified interstellar object sparks concerns over potential alien threat

Loeb, who is known for controversial ideas about extraterrestrial life, has warned that if the object is artificial, it could represent either a scientific breakthrough or a security risk. He noted the object’s trajectory will take it behind the sun in October before it potentially moves close to Earth between November 21 and December 5, 2025.

“The visitor is already in our backyard,” Loeb said, urging preparations for every possible scenario — whether peaceful or dangerous.

He has referred to the object as a possible “mothership,” a term suggesting it might carry smaller probes capable of exploring planets, including Earth. Loeb has also released three early research papers outlining the object’s behavior and has recommended that NASA consider intercepting it with the Juno spacecraft as it nears Jupiter.

Loeb further proposed creating an “interstellar risk scale,” which would help governments and scientists classify unknown space objects — from harmless comets to potential technological artifacts. He believes international coordination is essential, involving not just scientists but also policymakers and psychologists, to manage public communication and avoid panic.

An alien spacecraft? : Divided scientific opinion

Not all astronomers share Loeb’s concerns. Chris Lintott, a professor at the University of Oxford, dismissed the claim as unrealistic, arguing it risks distracting from serious study of the object’s properties.

Despite skepticism, Loeb points to several unusual details. At roughly 12 miles wide, 3I/ATLAS is larger than most interstellar objects previously recorded. Its high speed — nearly 60 miles per second relative to Earth — also makes it impossible for current spacecraft to intercept. Loeb argues that even if the likelihood of it being artificial is low, preparing for that possibility is prudent, comparing it to planning for unlikely but catastrophic risks.

Related: Harvard Physicist Says Interstellar Object Could Be Nuclear-Powered Spaceship