The STS-60 crew aboard Space Shuttle Discovery observed the display of the Aurora Australis or Southern Lights. The multi-hued shafts of light, extending upward to 200 miles above the Earth's surface, are caused by beams of energetic electrons colliding with the oxygen and nitrogen in the Earth's upper atmosphere. The strong red glow occurs at the highest altitude where the air is least dense and composed mostly of oxygen. At lower altitudes, the greater density favors the green color, also produced by atomic oxygen. Sometimes at the bottom (the lowest altitude of the aurora) a pink border is produced by nitrogen. Frames 037 and 038 are underexposed. Frame 036 was selected by the crew for release to the public.
