Thirty-three years ago, Voyager 1 looked back at Earth from the edge of our solar system, about 3.7 billion miles (6 billion kilometers) from the Sun. It saw, and photographed, a speck of blue floating alone in a sunbeam. The resulting picture of “the Pale Blue Dot” (as Carl Sagan termed it) shows the planet we all live on as a fraction of a pixel in a vast ocean of space. This unprecedented image and the resulting emotional impact of seeing our home planet as a vulnerable world captures the core mission of Astronomers for Planet Earth (A4E).