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The Earth talks, whistles and sings to us all the time. And scientists are still trying to understand everything the Earth is saying to us. Not only does the Earth sing and whistle to us but also puts on light shows for us at the same time.
The song the Earth sings to us is known as the “dawn chorus” and the light show is the Aurora Borealis or the Australis Borealis, the northern lights and southern lights. Several times a month usually starting at sunrise until mid-morning the Earth is singing the dawn chorus. It sounds like flocks of birds chirping and sometimes it can sound like hundreds of people whistling in rising and dropping tones. Once in awhile the song is eerie with hisses of different pitches and sliding tones, which stop and then start all over again.
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Northern Lights over Eielson AFB, Alaska
What actually is the cause of these sounds are high-energy particles from the sun as they hit the Earth’s Van Allen radiations belts, usually during times of active or high solar activity. Doesn’t it seem the scientific explanation isn’t as fun as the imagination. This is what is occurring though, as the sun ejects particles at a high rate of speed towards the Earth they interact with the magnetic fields of the planet causing these sounds in the radio spectrum. The dawn chorus can be heard in the ELF (extremely low frequency) and the VLF (very low frequency) ranges of the radio spectrum. To put some mystery back in, the dawn chorus doesn’t always occur during times of high solar activity, so all the reasons aren’t yet known for this phenomena.
The Earth also whistles to us, and the light show this time is lightning. Whistlers are caused by lightning strikes. At any given moment there are an estimated 300 to several thousand thunderstorms with over a million lightning strikes per day on the Earth. This creates a huge amount of electromagnetic energy all around the planet and can be heard in the ELF portion of the radio spectrum. A whistler is a burst of radio energy that sounds like a whistle falling in pitch and is initiated with a lightning strike.
A new science of listening to the Earth talk to us is gaining popularity among scientists who believe the Earth emits electromagnetic waves before an earthquake strikes. The theory is that electromagnetic pulses in the crust of the planet or disturbances in the ionosphere are caused by the fracturing of rocks before an earthquake and these rocks contain magnetic particles. These disturbances have occurred as much as two weeks before the main earthquake. Sometimes before a major earthquake, people have reported seeing lights in the sky. These lights could be electromagnetic disturbances caused by the fracturing of these magnetic rocks. These strange lights were seen in China before the large earthquake of May 12, 2008 in Sichuan, China. Hours before a 6.9 earthquake stuck Kobe, Japan there were 23 reported sightings of strange lights in the sky. Researchers at Stanford University noticed disturbances in the ELF radio band weeks before the 1989 San Francisco (World Series) earthquake.
Video of strange lights 30 minutes before the Sichuan, China earthquake
You can build your own ELF receiver and listen for these sounds but in the city the manmade noise usually drowns them out. A better way to hear the dawn chorus and whistlers would be to listen to recordings.
Factoid about the Van Allen belt
The Van Allen belt is a belt of electrically charged particles around the Earth at an altitude of about 4,000 miles (6,400 km), which are trapped and held in place by the Earths magnetic field. The Earth actually has two and maybe three radiation belts, the inner belt is the Van Allen belt, named after its discoverer, Dr. James Van Allen of the University of Iowa.
© 2009 Sam Montana
Interesting web sites
Recordings of the dawn chorus and whistlers - Univ. of Iowa
Recordings of the dawn chorus and whistlers
IEEE report on predicting earthquakes
YouTube video of lights before the Sichuan, China earthquake
YOU sing to my heart when you write gems like this one Sam!
Thank you Colin. Most people might not appreciate these sights and sounds, but when you think about where they come from, it is pretty awe inspiring.
Great article Sam! I never knew about these sounds in the very low frequency range. I know a little about the radio frequencies on the electromagnetic spectrum.. but didn't know about these sounds. Good job.