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If there are aliens out there, it might not be too hard for them to find us.
That’s because experts say alien civilizations can map our planet using signals from cell phone towers — the number of which has grown exponentially over the past 30 years.
They are now the second most powerful source of radio leakage on Earth – behind only military radar transmissions – and have overtaken the commercial radio and television stations of the 20th century.
To put this in context, each cell tower emits a radio signal with a power of 100-200 watts, equivalent to a total peak leakage of four gigawatts from our planet, according to researchers from the University of Mauritius and the University of Manchester.
It means that if aliens had a radio telescope equivalent to the £1.7 billion Square Kilometer Array (SKA) being built in South Africa and Australia and due to be ready by 2028, they would pretty much destroy our 4G activity. should be able to detect.
Cellular towers transmit most of their radio power parallel to the Earth’s surface, meaning a signal is strongest when it rises or sets on the horizon as seen from a future alien world
Massive numbers: Cell phone masts are now the second most powerful source of radio leakage on Earth — behind only military radar transmissions — overtaking the commercial radio and television stations of the 20th century (stock image)
Add to that the fact that the technology gets a boost for 5G — plus if radio leakage from individual cell phones themselves is taken into account — then things would be even easier, the new study finds.
Study researcher Dr. Nalini Heeralall-Issur, from the University of Mauritius, said: “I believe there is every chance that there are advanced civilizations and some are able to detect the man-made radio leakage from planet Earth.”
However, the aliens would have to be on a world within eight light-years of Earth to make it possible, the researchers say, and if only they had a telescope as powerful as today’s Green Bank Telescope in West Virginia, it would detecting us are unlikely.
Not only that, but where they are in the sky would also be a factor.
Since most cell phone towers are in the Northern Hemisphere, a planet with theoretical extraterrestrial life in the Northern Hemisphere sky would get a stronger signal than one in the Southern Hemisphere.
This is because cell towers transmit most of their radio power parallel to the Earth’s surface, meaning that a signal is strongest when it rises or sets on the horizon as seen from a future alien world.
Professor Mike Garrett, team leader on the project and director of the Jodrell Bank Center for Astrophysics at the University of Manchester, said: ‘I have heard many colleagues suggest that the Earth has become increasingly radio quiet in recent years – a claim I have always contested.
“While it is true that we have less powerful TV and radio stations today, the proliferation of mobile communication systems around the world is profound.”
He added: ‘While each system individually represents relatively low radio powers, the integrated spectrum of billions of these devices is significant.
“Current estimates suggest we will have more than 100,000 satellites in low Earth orbit and beyond before the end of the decade.
“Earth is already abnormally bright in the radio portion of the spectrum; if the trend continues, we could become easily detectable by any advanced civilization with the right technology.”
Covered: This map shows where all cell phone towers are located around the world today
While an alien civilization wouldn’t be able to eavesdrop on our conversations, the study reveals that aliens could still discover many other things about Earth, including the planet’s rotation and axial tilt.
They could also measure our land distribution and monitor how population levels change over time around the world.
In the new study, researchers modeled signals as seen by three nearby stars: Alpha Centauri, which is in the Southern Hemisphere sky and only four light-years away, plus Barnard’s Star and HD 95735 in the Northern Hemisphere sky.
The latter two are six light-years and eight light-years away, respectively.
None of these stars or their associated worlds are thought to be habitable.
“The main goal of the present study was to determine the power spectrum of cell towers on Earth as observed by a hypothetical civilization located at interstellar distances,” the researchers wrote.
Dreaming big: If aliens had a radio telescope equivalent to the £1.7 billion Square Kilometer Array (pictured) being built in South Africa and Australia and due to be ready by 2028, they’d make our 4G activity so should be able to detect
‘Our findings show that the leakage radiation from mobile towers is variable in intensity and periodic in nature due to their non-uniform distribution over the Earth’s surface and the rotation of our planet.’
The researchers found that any nearby civilization within 10 light-years of Earth and equipped with a receiving system similar to the Green Bank Telescope would not detect the leak from Earth’s cell tower.
Next-generation telescopes like SKA “could do better,” they added, and with the future development of 5G, “Earth leakage will continue to gain momentum over time.”
“If the spill can be detected, an alien observer could discern several details of our planet’s nature and the spread of technology on its surface,” the study concluded.
The research has been published in the Monthly communications from the Royal Astronomical Society.