This side-by-side comparison image shows Spitzer's Delta II rocket in the late afternoon before launch. On the left is a photograph in visible light, while on the right is a false-color infrared image showing the launch vehicle in the way Spitzer would see it. The coldest surfaces in the infrared image are blue/black while the hottest ones are yellow/white. The comparison between these two images reveals many interesting features of infrared light. In many places the infrared image almost mimics a photographic negative, with light objects in the visible photograph looking dark in the infrared and vice versa. This is not a simple photographic effect, but a result of the fact that darker surfaces absorb sunlight more efficiently and become hotter than lighter surfaces. This thermal evidence of light absorption is very obvious on the Delta rocket, where the white surfaces are cooler than the darker ones. Upon close examination, this is even obvious on the lettering and designs on the various labels on the rocket and adjacent tower. In all of these places the heat patterns in the infrared image highlight the darker colors. The infrared image also reveals a variety of features that can not be seen at all in the visible photograph. The rocket payload faring containing Spitzer is kept air conditioned, and several cool bands associated with this cooling can be seen on the upper white portion of the rocket. Also, the division between the lower empty fuel tanks and second stage rocket can be seen just below this as a cooler segment of the blue tube. The large gantry structure on the left shows a number of interesting thermal patterns. The hottest portion of the gantry is the area around the large white upper structure. Here the heat is being generated internally by the support and air conditioning equipment found in this structure, making it very hot even though it is painted white. The white panel on the upper right side of the gantry also shows some warm horizontal stripes. These trace the wamer metal beams on the inside of the panel that can't be seen in the photograph.