1. Inertia
Gravity
1. a tendency
1. a force
2. Newton’s 1st law
Both
1. keep
the planets in orbit
2. known forever
3. Keeps Earth from falling into the sun
3. Keeps Earth from flying off into space
4. Earth resist a change
in motion-wants to go straight at constant speed
4. Gets stronger as you get closer to Earth’s center

4. Rotation
Revolution
1. Determines a day on Earth (24 hours)
1. Determines a year on Earth (365 ¼ days)
2. Spins about the axis
Both
1. Ways Earth
moves
2. Moves around the sun
3. Makes the stars appear to move around Polaris (North Star)
3. Moves in an ellipse orbit.
4. Kept in orbit by earth’s Inertia and the sun’s gravity
4. Causes the sun to rise and set

5. ↑Latitude = Less Direct Light

6. Light is less direct at higher latitudes
Light is spread out over a greater area because Earth curves away
Light is more direct and overhead

8. 1. Means “sun stops” getting high overhead
June Solstice
September Equinox
1. Means “sun stops” getting high overhead
1. Means “equal nights”
2. Most direct light hits the tropic of Cancer
2. The most direct light hits the equator
Both
1. Last
one day
3. Summer starts w/ the most hours of daylight
3. Starts of Fall (Autumn) with 12 hours of daylight
4. North Axis/Hemisphere
tilts toward the sun
4. Neither North or South axis tilts toward the sun