The Pale Blue Dot is a photograph of planet Earth taken in 1990 by the Voyager 1 spacecraft from a record distance of about 6 billion kilometers from Earth, as part of the solar system Family Portrait series of images. In the photograph, Earth is shown as a tiny dot (0.12 pixel in size) against the vastness of space. The Voyager 1 spacecraft, which had completed its primary mission and was leaving the Solar System, was commanded by NASA to turn its camera around and to take a photograph of Earth across a great expanse of space, at the request of Carl Sagan.
This is an animated version of Carl Sagan's famous audio-text about The Earth,
pale blue dot
https://www.youtube.com/watch?v=nl5dlbCh8lY&feature=youtube_gdata_player