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

RAP

Key Questions1. 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 system located in the Milky Way?

• 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: 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.

Milky Way Galaxy = Spiral Galaxy

The Milky Way Galaxy

1. Number of Stars-200-400 billion

2. Diameter-100,000 light years3. Thickness-1,000 to 3,000 light

years4. All objects revolve around

center of the galaxy

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

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

Sun.

Local Cluster of Galaxies