Science & Space
Milky Way
The Milky Way is the barred spiral galaxy containing our solar system, billions of stars, gas, dust, and a central black hole.
The Milky Way is the barred spiral galaxy that contains the Sun, Earth, and the rest of our solar system. Its stellar disk spans more than 100,000 light-years and includes roughly 100 billion stars, along with gas and dust held together by gravity. The solar system lies in the Orion Spur, about 26,000 light-years from the galactic center.
From Earth, part of the galaxy appears as a faint, milky band across dark night skies because we view its disk from within. At the center lies Sagittarius A*, a supermassive black hole with a mass about four million times that of the Sun. Astronomers map the galaxy from inside using observations and computer models.
Quick facts
- The Milky Way is a barred spiral galaxy with two major spiral arms and two minor arms.
- Its stellar disk spans more than 100,000 light-years.
- The Sun is in the Orion Spur, between the Sagittarius and Perseus arms, about 26,000 light-years from the galactic center.
- The solar system takes approximately 230 million years to complete one orbit around the galactic center.
- Sagittarius A*, the supermassive black hole at the galaxy's center, has a mass about four million times that of the Sun.
A surprising fact
Every individual star visible in Earth's night sky without a telescope belongs to the Milky Way.
