When Voyager 1 spacecraft was leaving our solar system on February 14, 1990, engineers turned it around for a last look on Earth from 4 billion miles away. The picture of a tiny dot of light, among countless stars, inspired Dr Sagan to write a moving piece, entitled 'Pale Blue Dot'. Few words from it are quoted here. “Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic...