OXON HILL, MARYLAND, United States, EARTH, SOLAR SYSTEM, MILKY WAYWhen we look up, every star we see is in the Milky Way, the spiral galaxy we call home. The Milky Way holds every alien planet humans have ever spotted, and the billions more that likely exist in the galaxy.

On a dark night, the dense plane of the Milky Way winds like a ribbon across the sky. On a really dark night, in areas free from light pollution, that ribbon becomes so intensely spangled with stars that it’s possible to see the dark, dusty clouds of dust and gas deep in space that blot out their light. Those clouds are so prominent that Australia’s Aboriginal people saw them create the shape of an emu.

Our galactic home is one of