The northern lights, known as the aurora borealis, is one of nature’s most dazzling spectacles. Science is still not certain 16 exactly what these lights are and what causes them. Sometimes, the brilliant rays of light spread upward in the shape of a fan. 17 , they flash here and there like giant searchlights. Farther north, the aurora frequently looks like fiery draperies which hang from the sky and sway 18 while flames of red, orange, green, and blue play up and down the moving folds.
According to scientific measurements, this discharge of light 19 from 50 to 100 miles above the earth. It is seen 20 around the Hudson Bay region in Canada, in northern Scotland, and in southern Norway and Sweden.
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