While airport radars are primarily designed to track aircraft near airports, a recent study suggests they might also be inadvertently alerting alien civilizations to our existence. These systems emit electromagnetic waves into space, and scientists have found that these signals could be detected by extraterrestrial life as far as 200 light-years away—provided they have advanced technology similar to ours.
Presented at the Royal Astronomical Society’s National Astronomy Meeting 2025 in Durham, the research explored how Earth’s radar signals might appear to observers near stars like Barnard’s Star and AU Microscopii. Through simulations, the team discovered that even the relatively modest signals from civilian airport radars—producing around 2×10¹⁵ watts of combined radio power—are strong enough to be picked up by telescopes equivalent to the Green Bank Telescope in the U.S.
Military radars, which emit more concentrated and powerful signals, could be even more conspicuous. These systems can reach peak outputs of approximately 1×10¹⁴ watts in focused directions, making them around 100 times more detectable in certain parts of space. To an extraterrestrial observer with a capable radio telescope, such signals would likely appear unmistakably artificial—potentially serving as a clear indicator of intelligent life.
The researchers argue that any radar system on a technologically advanced planet could function as a universal signature of intelligent life. Beyond the implications for interstellar communication, the study also highlights the importance of understanding how human-made signals propagate through space. According to Michael Garrett of the University of Manchester, this knowledge can inform the future design of radar and communication systems, enhance our ability to monitor space for threats, and deepen our understanding of humanity’s growing impact on the space environment.
