1. Motion through the universe

2. Rotation Results in day/night.
24 hour period (measured by Earth’s equator.
Center of Earth is larger at center due to this spinning motion.

3. Precession Change in Earth’s tilt but NOT its 23.5⁰ angle.
Does NOT effect the seasons, only position of stars

4. Precession
Because the plane of Moon’s orbit is tilted away from plane of Earth’s elliptical plane

5. Nutation
Wobbling of precession motion (1/2 degree over 18 year period)
Due to gravitational pull of the Moon.
Can slightly increase or decrease seasonal affects

6. Nutation

7. Revolution (orbit) Occurs approx. 150 million km away
Perihelion – closest to the sun (Jan 3rd)
Aphelion – farthest away from the sun (July 4th)
Does this match what you would have guessed? Why or why not?

8. Seasonal Change
More influenced by TILT of Earth’s axis (23.5)