Earth's Hum Heard as Never Before
Earth hums, and scientists have for the first time recorded the sound in the ocean. Using seismometers in the Indian Ocean, researchers picked up on the sound that is way, way too low for mere human ears to hear, reports Live Science. No recording is available, but a Columbia University scientist not involved with the study in Geophysical Research Letters gives National Geographic a rough description: "It's like taking a piano and slamming all the keys at the same time," says Spahr Webb. "Except they're not nice harmonics. They're oddball frequencies." And ultra-low ones: Specifically, the hum is between 2.9 and 4.5 millihertz, and humans can only begin hearing things at about 20 hertz, or roughly 10,000 times higher.
While scientists have long known about the hum, and have previously recorded it on land, the new research could shed more light on the Earth's interior, and perhaps even help map distant planets, reports the Washington Post. The leading theory is that the hum is caused by waves interacting with each other at the bottom of the ocean, which results in vibrations being sent down into the Earth's crust. The process, however, is complex and not fully understood. For instance, "sometimes a wave on a shallow coast somewhere ripples over the rough sea floor and adds its own frequencies to the hum," per the Post. Whatever the exact reason, one thing is clear: the low drone is a constant one.
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Even though we can't feel it, the Earth is humming all the time. "If you played it at 10,000 times the speed, you could hear 'white noise' like an old TV set between channels," Fabrice Ardhuin, an oceanographer in France, tells the Huffington Post. Experts discovered the planet's very low vibrations in the late 1990s, and now researchers may be able to explain them, Live Science reports. According to Ardhuin's team, the hum is a result of ocean waves. Waves don't just occur at the ocean's surface, Live Science explains: They can reach to the bottom of the ocean. There, they move along a "bumpy" sea floor, creating pressure that leads to the Earth oscillating, the American Geophysical Union reports.
That could explain the so-called "microseismic" waves behind the hum—at least those lasting from 13 to 300 seconds, according to researchers' models. Shorter microseismic waves could be the result of waves crashing into each other. The wave theory isn't entirely new, Live Science notes, but the findings offer a fuller explanation of what could be happening. "I think (the results are) a relief to the seismologists," says the oceanographer. "Now we know where this ringing comes from, and the next question is: What can we do with it?" One possibility: The research could help experts spot earthquakes occurring a long distance away, AGU notes. (In other recent geological finds, it seems the Earth's core has a core of its own.)
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Space has no air, and therefore cannot project sound in audible wave form. As it says in the description, these sounds are not from satellites zooming around the earth with a normal microphone. Sohpisticated instruments can detect the different sonic vibrations going on in the planet.
What the remote sensors on the sattellite are doing is analyzing different radio frequencies coming off the surface of the earth and converting it into audible soundwaves to hear. You're merely hearing the general frequencies of the Earth in an audible format
That's awesome, Owl...