Hanging metal halide lamp1 is turned on at a certain interval and starts to turn slowly. It gradually glows brighter and increases its speed. The more its rotational speed increases, the higher the lamp rotates by the centrifugal force and hangs at an almost horizontal position. Viewer sees the lamp at eye level.
The brightness of the lamp is so intense that viewer cannot keep looking. Viewer also sees an afterimage of the light trajectory, which temporarily burns into the field of vision when he/she looks away from the lamp or closes eyes. This afterimage occurs not because of a high speed movement, but because the brightness exceeds the normal stimulus-response scheme of the human visual sense. The excess stimuli remain on the retina for a certain period of time and produce this light line.
The first image I had in my mind was a moth’s trajectory around a lamp. Moths are attracted to lamps because of their phototaxis. Phototaxis helps moths orient themselves during flight by using moonlight, a parallel light, as the guide. When moths are around a lamplight, a radiant light, their perceptibility limit causes them to fly parallel to a radiant light and form a spiral flight trajectory.
1 This type of lamp is normally used in factories or stadiums