1. Science Starter Pull out your homework (Don’t Turn it In)
How does Earth move in space?
Tell me at least 2 ways that Earth moves

2. Answer
Rotates (on its axis) and revolves (in an elliptical orbit)

3. HOMEWORK Study for your quiz (Monday) Planets Kepler’s Laws
Nutation & Precession

4. Agenda Science Starter Review Last Class
Intro to Precession & Nutation
Work on homework if you haven’t completed it

5. Review
Complete the worksheet on your desk

6. NOTES #5: PRECESSION & NUTATION
Why can’t we feel the Earth moving?

7. EARTH’S AXIS IS TILTED Earth does not sit straight in it’s orbit
It is tilted at a 23.5° angle

8. EARTH’S AXIS IS TILTED

9. THE AXIS CHANGES DIRECTION!
Precession – change in direction of the axis without change in tilt
This process takes THOUSANDS of years to occur
Due to the shape of Earth

10. PRECESSION
Think of it like spinning a top!

11. PRECESSION
See it in action!
Video Link

12. WOBBLE BABY, WOBBLE BABY…
Nutation – wobbling around the axis of the Earth that causes a slight change in tilt
This process is much faster… only 18 years!
Due to the moon and its gravitational pull
Think back to barycenter

13. NUTATION

14. YOUR ASSIGNMENT
Write a two-three paragraph essay to (10-14 sentences)…
Define the concepts of precession and nutation
Compare and contrast the processes
What do you know about Earth’s motion through space? Use your notes!
Your essay will be graded on…
Scientific correctness of definitions
Scientific correctness of comparisons and contrasts
At least one way they are similar and one way they are different
Following directions for length

15. Last night’s homework
I am going to give you 10 minutes to complete you homework from last night if you haven’t already