1. Galaxies and Star Clusters 14.11

2. What is a Galaxy? A huge collection of gas, dust and hundreds of billions of stars and planets. These stars are attracted to each other by the force of gravity and are constantly in motion. We are in the Milky Way Galaxy. The night sky looks like milk splashed across it.

3. We are in the arm of our Spiral Galaxy.

4. 14.11

5. Astronomers estimate that there are at least 400 billion stars in our Milky Way Galaxy. Galaxies come in various shapes: spiral, (like the Milky Way), barred spiral, elliptical, irregular

6. Spiral, barred spiral, elliptical, irregular (p. 439)

7. The Milky Way Activity Open books to page 461, Figure 2:  Draw and label the top and side views by dotting with pen or pencil.  On the back side create by dotting) and label the 4 types of galaxies. (p. 462 top paragraph) We know which way the stars are moving by the way the arms are arranged.

8. Quasar What is a Quasar? Objects that look like faint stars but emit up to 100x more energy than our entire galaxy. What is a light-year? The distance that light rays travel in one year. (9.46 x 10 12 km)

9. Star Clusters What is a star clusters ? Groups of stars that are fairly close and travel together. These clusters may have as few as 10 stars or as many as a million - too small to be called a galaxy. Ex. galaxy – city, star cluster - suburb

10. Questions 2, 3: P. 463 2. Arrange the following in order of size, starting with the largest: star cluster; galaxy; universe; star; planet. The largest object is the universe, followed by galaxy, star cluster, star, and planet. 3. A certain star is located 60 light-years away from us. Which galaxy do you think this star is in? The star must be located in our Milky Way Galaxy because our galaxy is huge, about 100,000 light-years across.