Earth seen from four billion miles away
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Voyager: Taking a picture of home

26 February 2013 Last updated at 17:39 GMT

The pale blue dot caught in a thin strip of light on the left of the this image is Earth.

Voyager 1 captured this image from a distance of six billion kilometres (four billion miles). In it Earth is less than a pixel in size.

The image, taken in 1990, prompted astronomer Carl Sagan to say simply: "That's here. That's home. That's us."

In this clip from the BBC Four documentary, Voyager: to the final frontier, Dallas Campbell describes how the picture came about.