Airports and Military Radars May Be Unwitting Beacons to Alien Civilizations

A new study reveals that Earth's civil and military radar systems may be inadvertently transmitting signals into space that could be detected by alien civilizations. These unintended electromagnetic emissions—especially from powerful radar systems—could serve as key indicators of intelligent life on Earth for any advanced extraterrestrial observers within 200 light-years.

Presented at the Royal Astronomical Society's National Astronomy Meeting 2025, the research highlights that major global airports such as Heathrow, Gatwick, and JFK emit a combined radar power output of up to 2 quadrillion watts(2×10¹⁵ W). This level of radiation is potentially detectable by instruments comparable to the Green Bank Telescope in West Virginia, even from a distance of 200 light-years. By contrast, Proxima b—the nearest potentially habitable exoplanet—is just 4 light-years away, though current space travel would still take thousands of years to reach it.

Military radars, due to their highly directional beams, produce even more recognizable signals. Their peak emissions can reach 100 trillion watts(1×10¹⁴ W), sweeping through space in a lighthouse-like pattern. For civilizations equipped with sophisticated radio telescopes, such signals would appear distinctly artificial, with signal strength potentially amplified by a factor of 100 from certain angles. The University of Manchester research team suggests these radar emissions could represent universal signatures of technological civilizations.

The findings provide a new perspective for the Search for Extraterrestrial Intelligence (SETI) and deepen our understanding of how visible Earth's technological footprint might be across the cosmos. The modeling techniques used also hold potential applications in astronomy, planetary defense, and assessments of human technology's impact on the space environment.