New research reveals that radar systems from civilian airports and military operations are inadvertently broadcasting Earth’s presence to potential advanced alien civilizations within 200 light-years.

The study simulated how electromagnetic leakage from human technology would appear to extraterrestrials possessing radio telescopes comparable to Earth’s best, like the Green Bank Telescope. This distance also defines the theoretical limit for us detecting similar alien civilizations.

Presented at the Royal Astronomical Society’s 2025 meeting, the research focused on signals from major airports like Heathrow, Gatwick, and JFK. By modeling how these signals propagate through space over time, the team assessed their visibility from nearby stars such as Barnard’s Star and AU Microscopii.

They calculated that the combined signal from global airport radars, constantly sweeping for aircraft, reaches a significant 2×10¹⁵ watts. This power level makes them detectable up to 200 light-years away. For perspective, the closest potentially habitable exoplanet, Proxima Centauri b, is only 4 light-years distant.

Military radar systems, being more focused and directional like sweeping lighthouse beams, produce a distinct artificial pattern. Their accumulated peak emission reaches about 1×10¹⁴ watts within an observer’s field of view.

Lead researcher Ramiro Caisse Saide (University of Manchester) stated this signal would appear “clearly artificial” to any advanced observers in interstellar space. The work not only aids the search for extraterrestrial intelligence by identifying strong “technosignatures” but also enhances understanding of how human technology appears from space. Co-researcher Professor Michael Garrett (University of Manchester) highlighted the practical benefits: “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.”

For more details, visit Royal Astronomical Society.