5 days ago
Can aliens spy on Earth? Scientists say our radar systems could give us away
Alien astronomers, even with inadequate technology, could recognise the radio signals from airports on Earth. This was revealed in an upcoming study that shows how aliens may be able to spy on us using our radio signals.
According to a study headed by researcher Ramiro Caisse Saide of the University of Manchester, radar systems used to monitor aircraft at major airports like Heathrow in London and JFK in New York may generate radio waves powerful enough to be detected by extraterrestrial civilisations up to 200 light-years away.
The researchers examined how radio waves from military and civilian radar operations travelled outside Earth. This was done to predict how they would seem when they reached nearby stars.
According to the findings that were presented at the National Astronomy Meeting (NAM) 2025 in Durham, UK, signals emitted from airports across the world are over 2,000 trillion watts. This is powerful enough to detect extraterrestrial planets that are 200 light-years away using the Green Bank Telescope, which happens to be the most sensitive telescope in the world and is located in Virginia, US.
By carefully simulating how these radar signals spread out from Earth over time and space, the researchers looked at how visible they would be from nearby stars such as Barnard's Star and AU Microscopii.
Out of roughly 1,000 star systems in that range, the nearest potentially habitable world beyond our solar system is Proxima Centauri b which is only 4.2 light-years away. Another key question is whether an astronomer from another planet could comprehend what we are communicating and seeing. The signal wouldn't be artificial because it would seem to rise and fall throughout a 24-hour period when several airports came into view of the extraterrestrial astronomers due to Earth's rotation.
Additionally, the study contributes to those on Earth who are searching for evidence of extraterrestrial intelligence in estimating how far away they would be able to spot a civilisation that is comparable to our own.
'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,' co-researcher Professor Michael Garret was quoted as saying by the Royal Astronomical Society.
Military radar systems, which are more focused, create a unique pattern – like a lighthouse beam. They have an accumulated peak emission reaching about 1×1014 watts in a given field of view of the observer. This, according to the researchers, is weaker than airport radar.
Caisse Saide, a PhD student, added, 'In this way, our work supports both the scientific quest to answer the question, 'Are we alone?' and practical efforts to manage the influence of technology on our world and beyond.'
