Comment Plasma, one way or another. (Score 1) 106
Actually, come to think of it, since it used one day a year, so what if the light source has 100,000 hours of useful runtime? Damn this fixation on longevity and efficiency!
I would make each vertex of the geodesic sphere a tungsten electrode (cooled if necessary) and have fairly high powered plasma arcs flowing across the ball's surface, switching directions, forming patterns, and suchlike. The viewers should avoid staring too long.