Physics
Signal Attenuation
Quick fact
A radio signal from a transmitter on Earth can travel millions of kilometers into space before becoming undetectable, yet the same signal may drop below usable strength after just a few kilometers on the ground due to atmospheric attenuation.
Why this is interesting
Have you ever noticed how your car radio crackles and fades as you drive away from a city? Why does the same signal that was crystal clear become a whisper of static over distance?