The "Asgard" hemisphere of Callisto (detail mgnf)

Caption NASA originale:"...Dominating the scene is the impact structure, Asgard, centered on the smooth, bright region near the middle of the picture and surrounded by concentric rings up to 1.700 kilometers in diameter. A second ringed structure with a diameter of about 500 kilometers can be seen to the north of Asgard, partially obscured by the more recent, bright-rayed crater, Burr. The icy materials excavated by the younger craters contrast sharply with the darker and redder coatings on older surfaces of this Moon..."