How did the star castor get its name?
Castor is one of the twin sons of Zeus and Leda along with Pollux the twins of the constellation Gemini.
Present estimates of the dimensions of the Milky Way galaxy place its diameter at roughly 100,000 light years. The star "Castor" in the constellation of Gemini is about 50 light years distant from our solar system, or roughly 0.05 percent of the distance across the galaxy. Castor is closer to us than your average next-door neighbor.