The Earth is making a weird noise, and researchers have no idea why

Thanks to humans, the Earth is a pretty noisy place. We're loud creatures -- certainly more so than any other animal ever to walk the planet -- and we're even louder when we get together with other humans. But the Earth isn't totally silent, even without noisy animals all over its surface, and scientists are trying to figure out why that is. For the very first time, researchers have captured an underwater recording of a mysterious noise that Earth has apparently be producing for eons, and they s...