1. What is the Milky Way Like? Chapter 31.1

2. Since we are inside it, we cannot see the whole galaxy Since we are inside it, we cannot see the whole galaxy From Earth, there is a band of stars across the sky. This is what we see because we’re looking through the galaxy edge on. From Earth, there is a band of stars across the sky. This is what we see because we’re looking through the galaxy edge on. By mapping the location of stars, astronomers were able to determine the center of the Milky Way By mapping the location of stars, astronomers were able to determine the center of the Milky Way This allowed them to determine that the Milky Way had a disc shape with a central “bulge” of stars. This allowed them to determine that the Milky Way had a disc shape with a central “bulge” of stars.

4. To determine if the Milky Way had spiral arms, astronomers had to map the density of hydrogen. To determine if the Milky Way had spiral arms, astronomers had to map the density of hydrogen. From this they determined that the Milky Way is a spiral galaxy, with about 100,000,000,000 (100 billion) stars, about 100,000 light-years across From this they determined that the Milky Way is a spiral galaxy, with about 100,000,000,000 (100 billion) stars, about 100,000 light-years across In the center is a massive black hole In the center is a massive black hole

5. Looking at the age of the stars, it was noted that the oldest stars are in the center of the galaxy and the globular clusters, and the youngest in the arms Looking at the age of the stars, it was noted that the oldest stars are in the center of the galaxy and the globular clusters, and the youngest in the arms This tells us that the galaxy first formed from a spherical cloud. The stars of the globular clusters formed, the cloud collapsed taking on a disc shape. The stars in the center formed, and finally the stars in the arms. This tells us that the galaxy first formed from a spherical cloud. The stars of the globular clusters formed, the cloud collapsed taking on a disc shape. The stars in the center formed, and finally the stars in the arms.