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 the time, allowing only a trifle of light from the bright Sun to peak through. ... NASA Official: Jay Norris. ...