The Milky Way galaxy is a barred spiral galaxy with a diameter generally estimated between about 100,000 and 200,000 light-years. Traditionally, the visible disk of the Milky Way is around 100,000 light-years across, with a thickness of about 1,000 light-years, but recent research suggests the galaxy's span may extend to roughly 200,000 light-years due to a faint outer scattering of stars
. In terms of structure, it has two major spiral arms (Perseus and Scutum- Centaurus), two minor arms, and smaller spurs, with our Solar System located in the Orion spur about 26,000–27,000 light-years from the galactic center
. The Milky Way contains roughly 100 to 400 billion stars and at least as many planets. Its total mass, including dark matter, is estimated at around 1.5 trillion solar masses, with visible matter distributed among stars, planets, gas, and dust
. To summarize key size figures:
- Diameter: 100,000 to 200,000 light-years across
- Thickness: about 1,000 light-years
- Number of stars: 100–400 billion
- Mass (including dark matter): ~1.5 trillion solar masses
Thus, the Milky Way is a vast, massive galaxy, large enough that light takes over 100,000 years to travel from one side to the other
