A Pale Blue Dot

In 1990, astronomer Carl Sagan convinced NASA to point Voyager 1's camera back toward Earth one last time. The probe had been traveling since 1977 and was now 3. 7 billion miles away, racing toward the edge of our solar system. What the camera captured was startling: our entire planet — every ocean, every continent, every human civilization — compressed into a single pale pixel suspended in a shaft of scattered sunlight.…