Did you know that our lovely little planet creates an eerie hum? Don't fret if you didn't: Our human ears can't detect it. But the hum, discovered in the late 1990s, is discernable to seismic instruments.
When waves crash into each other, as it turns out, they create a humming noise. Interestingly, slower-moving waves create longer sounds; while a quick wave's hum lasts only around 13 seconds, slower waves can produce a hum that lasts between 13 and 300 seconds.
This new discovery provides scientists with more insight into the ever-mysterious inner-workings of Earth. Already, we know that waves extend down to the seafloor; studying them can help us learn more about these large, yet unexplored (for obvious reasons) elements of our planet.
Science: cool, no?