How wide is the Milky Way?

The Milky Way is our home galaxy; its stellar disk is about 100,000 light-years across. Light would therefore take roughly 100,000 years to cross the disk from one side to the other. That is not the distance from Earth to the “end”: the Solar System lies about 26,000 light-years from the center, and the outer edge of the galactic disk is not sharply defined.