While scientists on Earth scan the skies using massive radio telescopes to search for intelligent extraterrestrial life, new research suggests that we might already be broadcasting our presence—loud and clear—into the cosmos.
Researchers at the Royal Astronomical Society’s National Astronomy Meeting revealed that Earth’s radar systems, especially those used at airports and military bases, emit powerful radio signals that could serve as technosignatures—indicators of intelligent life—to any alien civilisation watching from afar.
According to simulations conducted by Professor Michael Garrett and PhD candidate Ramiro Caisse Saide from the University of Manchester, even civilian airport radars—like those at Heathrow or Gatwick—shine out into space like cosmic beacons, visible to alien observers with technology similar to our own.
“I don’t think they need to be more than a few hundred years more advanced than we are,” said Prof Garrett. “They don’t need to be something like a Star Trek civilisation—just slightly ahead of us to detect our signals.”
Beacons in the Sky
Radar systems work by sending out beams of radio waves to detect aircraft and other objects. But these waves don’t just stay on Earth—they leak into space.
Researchers found that civilian airports alone can emit signals reaching up to two billion megawatts, a level so intense that a telescope like the Green Bank Telescope in the U.S. could detect it from 200 light-years away.
For comparison, Proxima Centauri b, the closest known potentially habitable planet, is only four light-years away—well within range of these emissions.
Military Radars: Even Louder
Even more revealing are military radar systems, which use highly focused, sweeping beams akin to a rotating lighthouse. Depending on where an observer is positioned in the galaxy, these signals could be up to 100 times stronger than those from airports.
“These would look clearly artificial to anyone watching from interstellar distances with a powerful radio telescope,” said Saide.
What This Means for Aliens—and Us
The study suggests that aliens with even slightly more advanced technology than ours could detect these artificial signals and recognize them as signs of intelligent life.
It also flips the SETI (Search for Extraterrestrial Intelligence) perspective: while we’re listening for alien signals, they may already be listening to us.
These emissions, known as technosignatures, are unintentionally revealing our technological footprint to the universe. While we may not yet know who’s out there, if anyone’s watching—they already know we’re here.