If you’re hoping that we can avoid the attention of alien civilizations by lying low, it’s a bit late now. A new study released by the Royal Astronomical Society indicates that our radar systems are already screaming our location to ET eavesdroppers.
The question that keeps cropping up in SETI circles is whether we should send radio messages to be intercepted by any alien civilizations out there or to keep shtoom just in case the recipient is less ET and more Vogons looking for a place to build a hyperspace bypass. It’s a quandary that occupies both undergrad common rooms and major academic conferences, but it turns out that the entire matter may be moot and may have been for about three quarters of a century.
The team, led by Ramiro Saide of the University of Manchester, developed a model that simulated the radar transmissions from civilian airports like Heathrow, Gatwick, and JFK International Airport as well as military radar systems and then calculated how this radar signature would look from six nearby stars, including Barnard’s Star, HD 48948, HD 40307, AU Microscopii, HD 216520, and LHS 475.
Barnard’s Star
It turns out that when it comes to high-powered directional radar signals, the Earth is screaming like a banshee and has been since the early years of the Cold War in the 1950s. According to the study, the combined civilian radar signals from our planet add up to a whopping 2×1016 watts, with military systems adding in a more focused and directional signal of 1×1014 watts. And it generates a radio signature that screams artificial technology.
This leakage from the Earth’s air traffic and defense systems means that we are extremely visible to anyone within 200 light years of us that has a radio telescope equivalent to the Green Bank Telescope in West Virginia. If we take into account earlier studies that included larger, more powerful telescopes like the defunct Arecibo Observatory that limit extends to over 60,000 light years.
In fact, this is not a recent development. In the early decades of the 20th century, we were silent from a radio signal point of view. Early radio systems were relatively low powered and couldn’t be detected much beyond our atmosphere without pumping in an insane amount of energy. The development of VHF television and microwave radar in the late 1930s changed this and the building of NORAD’s DEW Line radar early warning system to detect Warsaw Pact bombers and missiles coming over the North Pole turned our planet into a cosmic lighthouse.
“In fact, these military signals can appear up to a hundred times stronger from certain points in space, depending on where an observer is located,”said Saide. “Our findings suggest that radar signals – produced unintentionally by any planet with advanced technology and complex aviation systems – could act as a universal sign of intelligent life.”
So, we’re now faced with the question not of whether we should send messages but whether there’s anyone out there to receive them. Mind you, that also raises the question of how that message will be received. Will it be ignored as a mere curiosity? Will it be regarded as an invitation to return the favor and invite us to join a great galactic federation in peace and niceness? Or, if you share my more pessimistic (realistic?) mindset, will it be used to guide in the giant Dalek invasion fleet that will wipe us out as a matter of general principle?
Only time will tell. Until then, I think I’ll stock up on canned food.
The team’s research was presented at the Royal Astronomical Society’s National Astronomy Meeting 2025 in Durham, England
Source: Royal Astronomical Society
