On July 19, 2013, the Cassini spacecraft took a series of pictures of Saturn as it was backlit by the Sun. In those images, appearing as little more than a tiny dot 1.4 billion kilometers away, was the Earth.
NASA's Jet Propulsion Laboratory organized an event called "Wave at Saturn", encouraging people to go outside and wave at the ringed planet while the images were taken. They also encouraged people to take pictures of themselves waving, and to submit them to JPL. People did so, in droves, from 40 countries around the planet.
The folks at JPL collected the photos and did something astonishing and lovely: Using an image of Earth as the index, they created the fantastic montage of our planet, making what is essence a map of Earth as it was seen from Saturn at the time! It's a depiction of Earth using pictures from Earth as Cassini looked back at Earth.