Radar systems operated by civilian airports and military installations may inadvertently broadcast Earth's presence to technologically advanced alien civilizations, new research suggests. The study examined how the electromagnetic signals leaking from these systems would be seen by observers as far away as 200 light-years away, assuming they had radio telescopes comparable to those used on Earth. The findings also hint that we could theoretically detect similarly advanced alien civilizations within the same range.
Preliminary findings, presented at the Royal Astronomical Society's 2025 National Astronomy Meeting in Durham, highlight how major international airports such as Heathrow, Gatwick and New York's JFK emit detectable signals that could serve as indirect indicators of intelligent life.
The researchers used detailed simulations to track how radar signals emitted by the Earth propagate through space over time. Their goal is to determine how detectable these signals are in nearby star systems, including Barnard's Star and AU Microscope.
The animation above shows the average total power of radar systems at each airport, averaged over one-hour intervals. The figure below shows the change of the total power of airport radar leakage radiation with time. Taking the direction of Barnard's Star as the direction, the power change curve is drawn within 24 hours. Image source: Ramiro Saide/Professor Michael Garrett
Their analysis showed that an airport radar system used to monitor aircraft produces a total radio output power of 2×10¹⁵ watts. This intensity of radiation is enough to be detected by radio telescopes like the Green Bank Telescope in West Virginia, even 200 light-years away from Earth.
For perspective, Proxima Centauri b—the closest potentially habitable exoplanet to Earth—is only 4 light-years away. Even so, it would still take thousands of years for a spacecraft powered by current technology to get there.
Military radar systems are more focused and directional, capable of forming unique patterns—like a lighthouse beam sweeping across the sky—with a cumulative peak emitted power of about 1×1014 watts within an observer's specific field of view.
Radar systems used by civilian airports (such as Heathrow) and military operations inadvertently reveal our presence to potentially advanced alien civilizations due to their covert electromagnetic leakage. Image credit: Mick Lobb / Radar Scanner – Heathrow Airport / CC BY-SA 2.0
Lead researcher Ramiro Caisse Saide from the University of Manchester said the comet would look man-made to anyone looking from interstellar distances using powerful radio telescopes.
"In fact, these military signals can be a hundred times stronger from certain points in space, depending on where the observer is," the PhD student added. "Our results suggest that radar signatures - signals produced inadvertently by any planet with advanced technology and complex aviation systems - could serve as a universal sign of intelligent life."
The animation shows that the average total power of a single airport radar system and the total power of airport radar leakage radiation are the same as those observed by the AU microscope. Image source: Ramiro Saide/Professor Michael Garrett
He said the research not only helps guide searches for extraterrestrial civilizations by identifying promising technological signatures, but also deepens our understanding of how human technology is viewed from space.
Co-researcher Professor Michael Garrett, from the University of Manchester, said: "By understanding how our signals propagate in space, we gain valuable insights into how to protect the communications radio spectrum and design future radar systems. The methods developed for modeling and detecting these weak signals could also be used in astronomy, planetary defense and even monitoring the impact of human technology on the space environment."
PhD student Caisse Saide added: “In this way, our work supports both scientific exploration of the question ‘Are we alone?’ and practical efforts to manage the impact of technology on our world and the wider world.”
Compiled from /scitechdaily