OOPS?!?
Over the better part of the last century, humans have been creating an enormous "force field" around our planet that may provide protection against solar storms and other cosmic radiation, and it was entirely on accident! No one thought that trying to talk to submarines or testing bombs in space would have such a far reaching effect, and we're only recently learning what this force field is all about. Ready for a quick dose of Super Cool Science S#!t? Open wide!
Very Low Frequency (VLF) radio waves
Radio waves that fall between the frequencies of 3 and 30 kHz are labeled as Very Low Frequency, or VLF waves. This corresponds to a wavelength of 10-100 km, meaning they are able to resonate even around large obstacles like mountain ranges and buildings, and can even penetrate the surface of the Earth.
In a phenomenon known as the Earth-Ionosphere waveguide, Earth's ionosphere acts as a conductor, while the Earth itself acts as a ground, creating a waveguide in the space between that allows VLF waves to propagate around the globe.
We've been using VLF radio waves for decades, mostly for things like communicating with submarines, but they are also used in things like radio clocks and even the metal detectors one might use to "comb" a beach for treasure.
The force is with us!
VLF waves were only ever meant to be used on and underground, as their frequency is too low to carry audio. However, they can reach out into space, all the way, it seems, to the Van Allen Radiation Belts.
In fact, our use of VLF technology seems to be pushing the Van Allen belts further from the Earth than they were when detected in the 1960's, and at times, they can create a sort of barrier to incoming charged particles, offering some man-made protection from the Sun... This "VLF bubble", as it's come to be known, wasn't an intentional thing, but unlike many of our accidents in the past, this one might actually benefit us!
Read more about the Van Allen Radiation Belts at Space.com!
Get all the details on the Van Allen Probes directly from NASA!
References:
http://vlf.stanford.edu/research/introduction-vlf
https://www.nasa.gov/feature/goddard/2017/nasas-van-allen-probes-spot-man-made-barrier-shrouding-earth
