In 1990, after years of lobbying by Carl Sagan, Voyager 1 turned its camera back toward home from about 6 billion kilometres away and photographed Earth as a pale blue speck smaller than a single pixel — an image NASA had repeatedly resisted because it offered little scientific value, but that became one of the most famous photographs ever taken.
On 14 February 1990, the Voyager 1 spacecraft turned its cameras back toward the inner solar system and…
