The mysterious pulsing comet 3I/ATLAS revives debates on possible alien technology

China’s Tianwen-1 captures rare images of interstellar comet 3I/ATLAS

Scientists have been closely following 3I/ATLAS since its discovery this July, but interest really picked up when Harvard professor Avi Loeb called out what he calls a heartbeat-like pulse in the object's light. Its brightness, Loeb says, seems to rise and fall in a cycling pattern of 16.16 hours, almost like some kind of cosmic signal repeating with surprising consistency. He wrote about the strange pattern in a recent Medium post, where he questioned whether the pulses could be connected to an internal mechanism rather than a natural rotation.

The first interpretation that analysts provided was that the changes in brightness were a result of the rotation of the comet's nucleus. Loeb questioned this interpretation by pointing out that less than ten percent of the object's light comes from the nucleus itself. Most of the glow that's visible is generated by the coma, the cloud of gas and dust surrounding the nucleus. That means the rhythmic variations have to be coming from changes in the coma rather than from the middle of the comet itself.

Loeb postulates that such changes are best explained if periodic jets or puffs of gas are released at regular intervals. When these jets brighten the coma, they create a measurable pulse-a heartbeat of sorts. Images taken by the Hubble Space Telescope on July 21, 2025, support the idea of the glow in the coma accounting for most of the light seen. Loeb postulates that if these jets are controlled bursts rather than naturally occurring ones, then they could take on the qualities of artificial thrusters adjusting the object's trajectory.

Loeb writes with the caveat that, yes, there can be natural explanations for what's observed. A comet may have a pocket of ice that periodically vents as it rotates toward the sun. In that scenario, the coma would appear to brighten every time the sun heats up that particular side. However, Loeb also points out that if the object were artificial, the jets' directionality would not be dependent on its orientation toward the sun. Their pattern would follow some other kind of internal clock, almost like interstellar Morse code.

Loeb has also suggested that the object's unusual path toward Jupiter-where it is predicted to arrive this coming March-might be intentional. He speculated that such a trajectory could be used by an advanced civilization to position observational devices around a planet. NASA, however, still classifies 3I/ATLAS as a natural comet and has not supported any of Loeb's alternative explanations.

For the time being, 3I/ATLAS remains an interstellar enigma. Whether its pulse reflects a signature of natural processes or something far more unusual, scientists will continue tracking its journey through the solar system, watching for new clues hidden within its steady cosmic rhythm.