Surprisingly, you probably have heard sferics. Anytime you listen to a distant AM radio station the pops and static you hear are sferics. The cause of these sferics is quite simple, lightning. As the pulses of lightening jump between the clouds and the ground they generate the radio signals in the recording. Since there can be hundreds of strikes within the about 3 thousand mile detection area, a listener can have a hard time listening to an AM station. This is good news if you are recording sferics. They are the most reliable signals one can hear.

How does this fit into our space sounds? Many things can generate sferics. Solar activity can generate sferics. Huge lightning bolts on Saturn produce sferics that have been picked up by the Cassini spacecraft. Manmade sferics are also common. I have an electric fence in the country where I live. Should grass touch the electrified wire I hear signals like sferics.

These sferics are a good way to start your scavenger hunt. Good hunting.

Other Subjects