Milky Way Galaxy

Definition

The Milky Way Galaxy is the spiral galaxy that includes our Solar System, characterized by its barred structure and multiple spiral arms. It is one of billions of galaxies in the universe and contains over 200 billion stars.

5 Must Know Facts For Your Next Test

1. The Milky Way Galaxy has a diameter of about 100,000 light-years.
2. It contains a supermassive black hole at its center known as Sagittarius A*.
3. The Sun is located in one of the spiral arms called the Orion Arm, approximately 27,000 light-years from the galactic center.
4. The Milky Way rotates at different speeds at different radii; this differential rotation helps maintain its spiral structure.
5. Our galaxy is part of a local group that includes Andromeda and about 54 other smaller galaxies.

Review Questions

Related terms

Galaxy:

A vast system composed of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity.

Spiral Arms:

Regions in spiral galaxies with higher concentrations of stars and star-forming regions that extend outward from the central nucleus.

Sagittarius A*:

The supermassive black hole located at the center of our galaxy with a mass equivalent to about four million suns.