In 1859, taking account of small irregularities in Mercury's motion, French astronomer Urbain Le Verrier predicted the existence of a new planet in the solar system. The search for this hypothetical body, aka "Vulcan," continued well into the early 20th century. Come learn about the exhaustive search for Vulcan, the observations, debates, and personalities involved, as well as the role Einstein's theory of general relativity played in ending the search for the planet that never existed.