New research reveals that radar systems used at major international airports like Heathrow and Gatwick are sending out strong and detectable radio signals that can be seen from as far as 200 light-years away. The findings were presented this week at the Royal Astronomical Society’s National Astronomy Meeting in Durham and are based on detailed simulations led by PhD researcher Ramiro Caisse Saide at the University of Manchester.

The study models how Earth’s airport and military radar emissions would appear to observers located in nearby star systems. These signals, though not intended for space, do not remain confined to Earth. Once transmitted, they travel at the speed of light, spreading into the surrounding galaxy. Over time, this creates a distinct electromagnetic signature that can be detected by anyone with sufficiently advanced radio equipment.

Unlike focused transmissions aimed at contacting other civilizations, these emissions are byproducts of routine terrestrial activity. Civilian radar systems used for air traffic control emit broad and repetitive pulses of radio energy as they scan the skies. Military radars, often narrower in scope but stronger in direction, emit beams that sweep across large areas and repeat in a regular pattern. Both types of systems generate emissions strong enough to be noticed beyond the solar system.

According to the researchers, the combined output from Earth’s global radar network reaches approximately two thousand trillion watts. These levels were fed into simulations to calculate how Earth’s electromagnetic signature would look from six target star systems: Barnard’s Star, AU Microscopii, HD 40307, HD 48948, HD 216520, and LHS 475. All of these stars are within 100 light-years of Earth and some are known to host confirmed exoplanets.

For any civilization located around those stars with equipment similar in sensitivity to the Green Bank Telescope in the United States, the signal from Earth would be visible. The emissions would rise and fall depending on Earth’s rotation, producing a repeating pattern that would not appear natural. Civilian airport radars in particular would generate a steady pulse, shaped by the locations and orientations of the airports that produce them.