Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2002 July 29 A Setting Sun Trail Credit & Copyright: Anglo-Australian Observatory, Photograph by David Malin Explanation: The Sun appears to move on the sky because the Earth rotates. The extreme brightness of the Sun, however, makes it difficult to capture a sun-trail -- the path the Sun traces on the sky. To capture the above picture, a very dark filter covered the camera lens for most of...