Hint: it's not from space and it's not from inside your body. But it does represent something you're totally reliant on.

It's an electrograph of a brass wire gauge, made in 1900 to help show the wary public that electricity didn't come in just the form of tree-felling and fire-starting lightning. Scientists needed to prove that it was a safe thing to allow into their homes, and that involved visualizing electromagnetic waves in a way that the public could understand. This was one of the ways they did it. It just happens to look pretty awesome. [Wired; Photo courtesy San Francisco Museum of Modern Art]