While Earth’s astronomers scan the skies for signs of alien intelligence, it turns out extraterrestrials might already know we’re here—thanks to our airports.

New research unveiled at the Royal Astronomical Society’s National Astronomy Meeting shows that radar systems used at airports and military installations emit powerful radio signals that could be detected by alien civilizations across vast distances in space. These signals, known as “technosignatures,” could serve as a cosmic calling card, announcing our presence to any civilization with sufficiently advanced radio telescopes.

According to the study, airports like London’s Heathrow and Gatwick generate radio emissions so strong that they could be spotted from hundreds of light years away. Researchers simulated how Earth’s radio leakage would appear to alien observers and concluded that even a moderately advanced alien species—only a few hundred years ahead of us technologically—could detect them.

“You don’t need to be a Star Trek-level civilization to spot us,” explained Professor Michael Garrett, director of the Jodrell Bank Observatory and senior astrophysicist at the University of Manchester. “A relatively nearby civilization with instruments similar to our current radio telescopes could easily pick up these signals.”

Radar Beams as Interstellar Beacons

Radar systems at airports function by transmitting radio waves to track the location of planes. These waves, while mostly focused toward Earth’s atmosphere, leak out into space as unintentional signals.

Co-author Ramiro Caisse Saide, a PhD researcher at the University of Manchester, and Professor Garrett found that emissions from global civilian airports could reach two billion megawatts in peak intensity. That’s bright enough for instruments like the Green Bank Telescope in West Virginia to detect them from up to 200 light years away.

To put that into perspective, Proxima Centauri b, the closest known potentially habitable exoplanet, is just 4.2 light years from Earth—well within range to detect our radio chatter.

Military Radar: Even Louder

While civilian airport radars leak signals more diffusely, military radar systems are significantly more focused and powerful. These systems sweep the skies like lighthouses with beams that could appear 100 times brighter than those from commercial aviation.

“These military emissions would be unmistakably artificial to any civilization observing from afar,” said Saide. “They stand out in a way that would clearly indicate intelligent origin.”

Earth’s “Technosignature” in the Universe

The study underscores how Earth has already been broadcasting its presence unintentionally for decades. These signals, especially those from high-power radar systems, form a distinctive technosignature—evidence of intelligent life that advanced alien civilizations could identify without needing to visit.

As humans continue searching for life beyond Earth, this research is a reminder that the universe may already be aware of us. The question now is: Who might be listening?