Interstellar Comet 3I/ATLAS emits First-Ever Detected Radio Signals, Confirmed as Natural Phenomenon
Astronomers have, for the first time, detected radio signals emanating from the interstellar comet 3I/ATLAS, marking a significant milestone in the study of objects originating outside our solar system. The detection, made through observations of hydroxyl (OH) molecules, confirms the comet’s presence and provides insights into its composition and behavior. however, initial speculation about the signals perhaps indicating extraterrestrial intelligence has been definitively ruled out, with scientists attributing the emissions to standard comet chemistry.
The breakthrough observation occurred on October 24,2025,revealing OH lines with velocities of +/-0.17 km/s and full widths at half maximum (FWHMs) of 0.88+/-0.37 km/s and 1.26+/-0.40 km/s. Integrated fluxes measured -7.9+/-2.9 mJy km/s and -19.1+/-5.2 mJy km/s. This detection is notably noteworthy as previous attempts to observe these lines with the MeerKAT telescope on September 20 and 28, 2025, were unsuccessful, with noise levels of 3 mJy/beam and 1 mJy/beam respectively. The signals are consistent with expected OH level populations based on the comet’s heliocentric velocity.
The source of the radio waves is understood to be the breakdown of water molecules on the comet’s surface. professor Avi Loeb explained in a blog post that the observed thermal broadening of the OH lines – approximately 0.8 kilometers per second – aligns with calculations based on a surface temperature of around 230 degrees Kelvin, given the comet’s distance of 1.38 times the Earth-Sun separation.
“This absorption signal constitutes the first radio detection of 3I/ATLAS,” loeb stated. ”So it’s just a fingerprint of water molecules breaking down on the comet. Basic comet chemistry. No whisper by an extraterrestrial intelligence, folks.”
3I/ATLAS, an interstellar comet originating from beyond our solar system, has garnered significant attention due to its unique trajectory and composition. The comet is currently visible from Earth, offering opportunities for further observation and study. This latest detection provides valuable data for understanding the characteristics of interstellar objects and the processes that occur within them, contributing to a broader understanding of the universe beyond our solar neighborhood.
