Your Place in the Galaxy

The Milky Way is vast but knowable:

• It spans roughly 100,000 light-years and holds 100-400 billion stars
• The Sun sits in the Orion Arm, 26,000 light-years from the center
• One galactic orbit takes 225 million years at 230 km/s
• Sagittarius A* at the center has about 4 million solar masses
• The disk is only 1,000 light-years thick, wrapped in a halo of old stars and dark matter