Back in the CB craze days, I had a car with a long whip antenna on the rear bumper. One night while parked under a street lamp, I happened to swat the antenna as I passed by and watch the a similar display - when whipping it back and forth, I could see 20 antennas, all of which appeared to be stationary. It's all based on the light wavelength...and in the original above, the shutter speed of the camera.