Milky Way

Definition

The Milky Way is the galaxy that contains our Solar System, characterized by its spiral shape and vast number of stars, planets, and other celestial objects. It is part of the Local Group of galaxies within the universe.

5 Must Know Facts For Your Next Test

1. The Milky Way has a diameter of about 100,000 light-years.
2. It contains an estimated 100 to 400 billion stars.
3. The Sun is located in one of the Milky Way's spiral arms, approximately 27,000 light-years from the Galactic Center.
4. The mass of the Milky Way is estimated to be around $1.5 \times 10^{12}$ solar masses.
5. Newton's Law of Universal Gravitation helps explain the gravitational forces that bind the Milky Way together.

Review Questions

• What is the approximate diameter of the Milky Way?
• How does Newton's Law of Universal Gravitation apply to the structure and behavior of the Milky Way?
• Where is our Solar System located within the Milky Way?

Related terms

Spiral Galaxy: A type of galaxy characterized by a flat, rotating disk containing stars, gas, and dust, along with a central bulge composed mostly of older stars.

Local Group: A group of more than 50 galaxies that includes the Milky Way and its nearest neighbors such as Andromeda and Triangulum galaxies.

Galactic Center: The rotational center of a galaxy. In the case of the Milky Way, it contains a supermassive black hole known as Sagittarius A*.