Could aliens detect Earth using airport radar? Scientists investigate

 

Earth's airports may be broadcasting our existence to the galaxy without anyone intending to. A 2025 study from the University of Manchester found that radar systems at major airports emit a combined signal of 2×10¹⁵ watts, strong enough for a civilisation with a telescope as sensitive as West Virginia's Green Bank Telescope to detect from 200 light-years away.

Lead researcher Ramiro Caisse Saide and his team, including Professor Michael Garrett, modelled how radar from hubs like London's Heathrow and Gatwick and New York's JFK spreads outward through space over time.

They then simulated how that signal would appear from the vantage point of nearby star systems, including Barnard's Star and AU Microscopii.

However, civilian airport radar was not the sole source that had been taken into account. The radar systems used by military planes emit radiation in a more directed beam with an emission peak of about 1×10¹⁴ watts.

According to Caisse Saide, such a directed beam would be seen as "artificial for certain" to those who observe the emissions from interstellar space using radio telescopes, and it can be one hundred times stronger than civilian emissions.

The reason for highlighting Barnard's star is the presence of a rocky planet named Barnard b in its orbit. It serves as a constant reminder that any potential radar leakage from these exoplanets would be precisely what humans need to tune into with their telescopes for searching for technosignatures from these worlds.

According to Garrett, some practical uses for the results include conserving radio frequency spectrums for communication and optimising the designs of radars. Caisse Saide emphasised that the same modelling process can be used for planetary defence and understanding the effects of humanity's technology on its space environment.