Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. Aurora , also known as the northern and southern lights, appear as luminous bands or streamers of light which can extend to altitudes of 200 miles. They are typically visible from the Earth's surface at high latitudes and are triggered by high energy particles from the Sun . The delicate colors are caused by energetic electrons colliding with oxygen and nitrogen molecules in the upper atmosphere. In this picture , the rear structure of the shuttle Endeavour is in the foreground with the vertical tail fin pointed toward Earth.
Star trails are the short streaks above Earth's horizon.
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