1. 1._____began from a nebula that was disturbed (big bang) 2._____observed the phases of Venus (astronomers) 3._____theory of the sun centered view of the solar system (astronomers) 4. _____causes day and night, winds and currents to curve (rotation and revolution) 5._____ changing wind direction keeps what going Do Now

2. 1.What is a light year? 2.What is a galaxy? 3.What are the three types of galaxies? 4.What is the name of the galaxy our solar system is located in? 5.What type of galaxy is the Milky Way? 6.Where is our solar sytem located in the Milky Way?

3. 1. A light year is the distance light travels in a year. 1light year=9.5 trillion kilometers 2. A galaxy is a large group of stars in space. 3. The three types of galaxies are spiral, elliptical (oval), and irregular. 4. The Milky Way Galaxy 5. It is a barred spiral galaxy with a bulge in the middle (cooler yellow stars) and spiral arms that spin out (made of hot blue stars) 6. Our solar system is located on an outer arm called the Orion arm.

4. Milky Way Galaxy = Spiral Galaxy

5. The Milky Way Galaxy 1.Number of Stars-200-400 billion 2.Diameter-100,000 light years 3.Thickness-1,000 to 3,000 light years 4.All objects revolve around center of the galaxy

6. The Milky Way Galaxy 5. Location of our solar system-outer arm 6. Distance from the sun to the center of the galaxy-30,000 light years 7. Galactic Year (period of revolution of our solar system) -240 million years

7. Local Stellar Cluster = A local group of stars that includes our Sun.

8. Local Cluster of Galaxies