How fast am I moving right now?

It may seem like an easy question, but it’s actually quite complicated — and perhaps best answered by another question: “Relative to what?”

Even when you think you’re standing still, the Earth is moving relative to the Sun, which is moving relative to the Milky Way, which is…you get the idea. Tucker Hiatt unravels the concepts of absolute and relative speed in this excellent TED-Ed video.