WASD to move the source of waves. Arrow Keys to move the observer. The Doppler effect affects any kind of waves; Light, Sound, ripples in water... You can observe the effect by moving the observer or the wave source- as they get closer, waves hit faster, and vice versa. This is the same for light, but instead of pitch, it can actually change its color in a phenomenon known as redshift. I'm not going to explain it all here- try it out yourself!
