Don’t book a room anywhere near Santa’s workshop if your goal is to observe the northern lights overhead. The aurora usually appear as a ring around the earth’s magnetic poles, called an auroral oval, with a diameter of about 2,500 miles. Consider a visit to Alaska, Denmark, or Iceland if it’s straight-up amazing light shows you’re looking for.
The crew of the International Space Station was passing over Mongolia, looking north toward Russia, when this image was taken. Notice the relative positions of the yellowish line that marks the edge of earth’s atmosphere, and the vivid green auroral display. What does this tell us about where in the atmosphere the aurora form?