Aliens could map the Earth based on cell phone towers

 Mobile phones are so ubiquitous that we no longer think about how they work. The key to their operation is the sheer number of radio transmission towers.

These cell towers cover a large percentage of the earth’s surface, especially in densely populated areas, and they constantly transmit microwave signals. Considering that all these cell towers are emitting all these radio signals, it’s a funny question whether these signals can be detected by an alien civilization.

The answer to this question was recently published in the Monthly Notices of the Royal Astronomical Society. The article talks about how radio signals entering space have changed over time.

In the 20th century, the bulk of radio broadcasts were from commercial radio and television stations. Now these transmissions are negligible compared to mobile communications. Military radar transmissions are still the most powerful source of radio leakage from Earth, but cell towers are now in second place....<<<Read More>>>...