For decades, scientists have been searching for evidence of alien civilizations in a collective effort known as the Search for Extraterrestrial Intelligence (SETI). Recently, China's Five-hundred-meter Aperture Spherical Radio Telescope (FAST) has joined this quest. In late August, researchers associated with FAST announced a significant finding while surveying 33 planetary systems. They reported the detection of a narrowband radio signal emanating from the direction of the planetary system K2-155, located 238 light-years away.
K2-155 hosts a super-Earth type exoplanet, designated K2-155 d, which is considered potentially habitable. This exoplanet orbits a red dwarf star and has a radius 1.6 times that of Earth. However, scientists caution that there is insufficient information to confidently assert that this world is a likely candidate for the emergence of life.
The signal was originally detected by FAST in 2021 but went unnoticed until the research team utilized a new machine-learning search pipeline designed to differentiate genuine signals from terrestrial radio interference. The intriguing results were published in The Astronomical Journal on August 27, 2026.
During the survey, researchers identified 139,127 initial candidates, which were subsequently narrowed down to two promising signals. One of these signals, originating from the star Kepler-438, was ultimately determined to be terrestrial interference. The signal from K2-155, detected at a frequency of 1148.4167 megahertz, appeared to pass initial tests that astronomers use to distinguish between natural cosmic signals and artificial signals generated by human activity.
The narrowband nature of the signal is particularly noteworthy, as natural sources rarely produce such signals, which are typically associated with artificial origins. Additionally, the signal exhibited a drift, likely due to the Doppler effect caused by the planet's rotation and orbit around its host star. This drift is another characteristic that could suggest an artificial source.
However, terrestrial interference can also mimic this drift, complicating the analysis. Another consideration is the localization of the signal in the sky; ideally, it should be confined to a single location. The K2-155 signal was indeed found in one spot, which is another point in favor of its potential alien origin.
Despite these promising indicators, there were also challenges. The signal was only strong in one polarization channel of the telescope, and similar signals were detected at three other stars near the same frequency, which raises the possibility of terrestrial interference being the source. The researchers remain uncertain about the origin of the signal.
As it stands, the source of the K2-155 signal remains unknown. While the possibility of it being an alien signal cannot be entirely dismissed, current evidence leans towards a more terrestrial explanation. Therefore, the conclusion drawn by the researchers is that the signal detected by China's FAST radio telescope is likely not of alien origin. Paranormal Country has not confirmed this information.
Image: Paranormal Country · Source: earthsky.org