Radar from airports and military systems may expose Earth to alien detection. These signals could be used to find intelligent civilizations.
New research indicates that radar systems operated by both civilian airports and military facilities may be unintentionally broadcasting Earth’s presence to technologically advanced alien civilizations.
The investigation examined how electromagnetic signals that leak from these systems could appear to observers located as far as 200 light-years away, assuming they possess advanced radio telescopes comparable to those used on Earth. The findings also imply that we could, in theory, detect similarly advanced alien civilizations within the same range.
Initial findings, presented at the Royal Astronomical Society’s National Astronomy Meeting 2025 in Durham, highlight how major international airports, including Heathrow, Gatwick, and New York’s JFK, emit detectable signals that could serve as indirect indicators of intelligent life.
Simulations trace signal visibility
The researchers used detailed simulations to track how radar signals emitted from Earth travel through space over time. Their goal was to determine how detectable these signals would be from nearby stellar systems, including Barnard’s Star and AU Microscopii.
In the upper panel, the animation shows the average total power of individual airport radar systems, averaged over one-hour intervals. The lower panel reveals the total power of airport radar leakage radiation as a function of time, plotted over a 24-hour period in the direction of Barnard’s Star. Credit: Ramiro Saide/Professor Michael Garrett
Their analysis showed that airport radar systems, designed to monitor aircraft, generate a combined radio output of 2×10¹⁵ watts. This level of emission is strong enough to be detected up to 200 light-years away by radio telescopes with capabilities similar to the Green Bank Telescope in West Virginia.
For perspective, Proxima Centauri b—the closest potentially habitable exoplanet—is located just 4 light-years from Earth. Even so, a spacecraft powered by current technology would still require several thousand years to reach it.
Military radars are more detectable
Military radar systems, which are more focused and directional, create a unique pattern – like a lighthouse beam sweeping the sky – have an accumulated peak emission reaching about 1×1014 watts in a given field-of-view of the observer.
This, lead researcher Ramiro Caisse Saide at the University of Manchester said, would look “clearly artificial to anyone watching from interstellar distances with powerful radio telescopes”.
“In fact, these military signals can appear up to a hundred times stronger from certain points in space, depending on where an observer is located,” the PhD student added.
Technosignatures and SETI implications
“Our findings suggest that radar signals – produced unintentionally by any planet with advanced technology and complex aviation system – could act as a universal sign of intelligent life.”
This animation reveals the same average total power of individual airport radar systems and total power of airport radar leakage radiation as would be seen from AU Microscopii. Credit: Ramiro Saide/Professor Michael Garrett
He said the research not only helps guide the search for extraterrestrial civilizations by identifying promising technosignatures, but also deepens our understanding of how human technology may be seen from space.
“By learning how our signals travel through space, we gain valuable insights into how to protect the radio spectrum for communications and design future radar systems,” said co-researcher Professor Michael Garrett, of the University of Manchester.
“The methods developed for modelling and detecting these weak signals can also be used in astronomy, planetary defense, and even in monitoring the impact of human technology on our space environment.”
Caisse Saide, a PhD student, added: “In this way, our work supports both the scientific quest to answer the question ‘Are we alone?’ and practical efforts to manage the influence of technology on our world and beyond.”
Meeting: National Astronomy Meeting 2025
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4 Comments
Aliens would bring us freedom.
Just think. The signals from the very British invention that defeated the dreaded Hun’s Luftwaffe could be enticing aliens to invade us! AAAAAAAAAAAAAAAAAAAAAAAAAGH! But then, as with the Germans, they would be so advanced technologically that they wouldn’t conceive of the electromag radiation as something created by humans, if they have any inkling of what primitive tribal barbarians we are.
I think I’ll just go watch “Earth vs the Flying Saucers” and be done with it.
If they could come, they already would have.