Between about December 1 and the winter solstice on December 23, a light effect not anticipated by the designers occurs.  Between 1:00 and 2:00 pm, the low winter sun grazes the side of the skyscraper in the background.  The building acts like the Earth's horizon and begins to make an artificial sunset. The light from the building grazes the edge of the round poles on the west outer ring pier and is diffracted.  A red and green "sunset" faintly appears projected on the plaza's pavement. (A summer photo is shown here for illustrative purposes.)