The fireball raging through the top of this image is actually a storm. It had already been on the move through the planet's atmosphere for several months when the images for this false-color mosaic were taken on January 11, 2011.
Twelve images were taken over the course of an hour, each with a different filter to show the varying degrees of methane absorption in the layers of the planet's atmosphere. Clouds deep in the lower atmosphere appear red and orange. The next higher are yellow and green. High clouds and haze appear blue and white. The bright blue color is the planet's rings which are outside the atmosphere altogether.