A Complete Aurora

Explanation : Aurora frequently make complete rings around a pole of the Earth. This particular “ crown ”, visible in orange near the top of this image , was taken by the orbiting Polar spacecraft about one year ago and released by NASA last month. A complete aurora l oval is normally hard to photograph because part of it usually occurs over a brightly sunlit portion of the Earth. Polar 's Earth Camera , however, can be programmed to filter out all but a certain type of ultraviolet light . In this “color”, atmospheric oxygen can glow brighter than reflected sunlight. People with normal eyesight living near the Great Lakes in North America would have been able to see this aurora , were it not daytime!