Mysterious, ultra low-frequency noises detected in Earth’s atmosphere — and scientists can’t explain them

Photo voltaic-powered balloons launched into the Earth’s stratosphere have recorded a collection of mysterious rumblings, and scientists cannot pinpoint their origins.

The noises, detected by specialised devices at 70,000 toes above the Earth’s floor, are often known as infrasound as a result of they’re so low-pitched they’re inaudible to human ears. Picked out from amongst a wash of hidden low-frequency sounds — together with thunder, ocean waves, rocket launches, cities, wind generators and even planes, trains and cars — the unusual infrasounds have up to now defied rationalization.