Humanity’s Complete Record of Radio-Active Comets and the Unexplained Frequency from 3I/ATLAS

In my reporting and research, I found that only a defined group of comets have ever been successfully detected in radio wavelengths: Kohoutek, West, Bradfield, Austin, IRAS–Araki–Alcock, Wilson, Levy, Hyakutake, Hale–Bopp, Ikeya–Zhang, LINEAR, NEAT, Holmes, Lulin, Siding Spring, Lovejoy, ATLAS (2019 Y4), and NEOWISE.

Halley’s Comet remains the most famous example, detected in multiple radio lines and later studied by the Vega spacecraft, where its emissions were measured in unprecedented detail. The Rosetta mission later expanded that record through its direct radio sensing of comet 67P/Churyumov–Gerasimenko. Altogether, counting each confirmed case of natural radio emission or radar reflection, we have roughly twenty examples across fifty years of modern radio astronomy.

That is the entire list. That is all of them. And every one of those detections reflects ordinary physics—thermal noise, hydroxyl-related emission, molecular rotation lines, radar echoes, and coma activity from volatiles boiling off the nucleus as the Sun heats them. Not one of those comets ever produced a narrow-band, discrete, water-hole absorption signature like the one detected from 3I/ATLAS on October 24, 2025.