The Milky Way's name stems from the Greeks, who referred to the galaxy as galaxias kyklos, or milky circle. The Romans, who called it via lactea, or "the road of milk," altered the term from its original Greek origins.
The word origins of the Milky Way's name are clear, but the stories surrounding it are a bit murky. One common belief is that the name stems from ancient Greek mythology. In this case, the mythological explanation for the name is that a beautiful mortal named Alcmene tricked a goddess named Hera into suckling baby Heracles, the son of her husband, Zeus. When Hera discovered who the baby was, she promptly tore him away from her breast, spurting her milk across the sky in the process.
Yet another legend about the creation of the Milky Way stems from the actions of Phaethon, the son of Helios, the sun god. Phaeton reportedly used his father's sun chariot to set the heavens on fire, resulting in the Milky Way.
Despite its early origins, it wasn't until the 18th century that people realized that the Milky Way is a galaxy of stars. Scientists discovered that the Milky Way is one of millions of galaxies around the universe in the 19th and 20th centuries.