A massive object from beyond our solar system is raising eyebrows in the scientific community — and sparking bold new theories. The interstellar body known as 3I/ATLAS, currently speeding through the inner solar system, appears to be emitting its own light rather than reflecting sunlight, according to Harvard astrophysicist Avi Loeb.
In a new blog post, Loeb challenges NASA’s classification of 3I/ATLAS as a comet. Analyzing NASA-released photos, Loeb and a colleague concluded that the light surrounding the object seems to come from the object itself — not from reflected sunlight. He notes that the brightness pattern suggests the light is concentrated around the object’s nucleus, potentially indicating that it’s self-luminous.
This finding, if confirmed, would mean that 3I/ATLAS is likely much smaller than previously thought — possibly under 100 meters in diameter — rather than the 12-mile-long size estimated under the assumption it was merely reflecting light. That would place it in the size range of the only two other known interstellar visitors: ‘Oumuamua and Borisov.
Loeb offered two hypotheses for the object’s apparent light emission. One is a natural source: a rare, radioactive fragment from the core of a nearby supernova. But he concedes that this is highly improbable due to the scarcity of radioactive elements in deep space.
His second theory is far more provocative: 3I/ATLAS could be a spacecraft powered by nuclear energy, shedding dust accumulated during interstellar travel. He stops short of claiming it is definitively alien in origin, but argues that the possibility “cannot be ruled out” without further evidence.
Adding to the mystery, Loeb points to the object’s unusually precise trajectory, which will take it behind the sun — and out of Earth’s view — just as it reaches its closest approach. It will also pass near Mars and Jupiter, prompting Loeb to speculate it may be conducting a reconnaissance mission.
He’s now urging NASA to act. Loeb has called on the agency to use the Mars Reconnaissance Orbiter’s HiRISE camera to capture images when 3I/ATLAS passes within 17 million miles of Mars in early October. He also wants NASA’s Juno spacecraft, currently orbiting Jupiter, to observe the object during its flyby next spring.
Whether 3I/ATLAS is a natural oddity or something more exotic, Loeb believes it deserves a closer look.
