1. Sun-Earth-Moon Interactions
Our Solar System
Sun-Earth-Moon Interactions

2. Two Solar System Models . . .
Geocentric
“Earth-centered”
Planets orbit around Earth
Partially explains the motions of the planets
Rejected model

3. Two Solar System Models . . .
Heliocentric
“Sun-centered”
Planets orbit sun
Explains most motions of the planets
Accepted model—better explanation of planetary motions!

4. Earth-Sun System
The Earth’s revolution (path/orbit around) around our sun is . . .
Counterclockwise!!!
At perihelion when closest to sun in January!
At aphelion when farthest from sun in July!

5. Our Sun . . . is NOT stationary !
Planets pull on it as they revolve
Pulls cause sun to orbit the solar system’s barycenter (balance of masses of sun and orbiting planets).
The sun is moving within our solar system but not much!

6. Earth-Moon System The moon is . . . Earth’s only satellite
Approximately the same age as Earth
The moon’s gravitational pull on Earth’s oceans produces tides.
The sun’s gravity does too BUT the moon is so much closer that it is responsible for most tidal action!

7. Earth-Moon System The moon’s revolution of Earth is . . .
Counterclockwise!
At Perigee when closest to Earth
At Apogee when farthest from Earth

8. Sizing the Solar System
Stop about 6:30