1. 7.1: The Earth’s Role in our Solar System
December 12, 2012
Additional Resources:
Barycenter: 

2. Warm-Up Explain how the Earth moves around in space
If the planet we live on is constantly in motion, does that mean we are moving right now? Explain.
Why do we experience seasons on Earth?
Do you think other planets experience seasons? Why or why not?

3. Objective
SWBAT explain how the earth moves around the solar system by writing about precession, nutation, and barycenter.

4. Agenda Warm-Up (10) Boy Genius (6) Today’s Notes (15)
Stations, Artwork, and Dancing (kind of) (24)
Real-World (literally) Application (25)
Exit Ticket (10)

5. Today’s Exit Ticket: 11 points
Draw the shape of Earth’s orbit around the sun. (1 pt)
Explain why Earth takes the path you drew in question #1. (1 pt)
What is the angle of the Earth’s tilt on its axis? (1 pt)
Explain what Kepler’s law tells us. (1 pt)
Explain why the sun is always in motion. Use both the sun and Earth in your example. (1 pt)
Explain how Earth moves about the solar system (be sure to use rotate, revolve, nutation, precession, and barycenter, in your response). (5 pts)

6. Check this Kid Out…
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7. Notes on the Universe
The universe is made of galaxies which are made of many stars. Some stars have planetary systems similar to our solar system. Earth is a satellite planet of one particular star (our sun)

8. The (whole) Earth moves in 3 ways.
The Earth:
1.Rotates (Rotation)
2.Orbits
3.Revolves (Revolution)

9. The earth rotates on its axis.
Rotates = spins.
The earth makes 1 full rotation every 24 hours.

10. The axis of the Earth is tilted at an angle of 23. 5 degrees
The axis of the Earth is tilted at an angle of 23.5 degrees. The axis always points towards the North Star.

11. We have day and night because of the Earth’s rotation.

12. DRAW A PICTURE OF THE EARTH TILTED ON ITS AXIS…

13. The Earth also revolves around the sun in an elliptical orbit.
The earth makes one full revolution around the sun every days days = 1 year

14. Kepler’s Three Laws of Planetary Motion (A Summary)
Each planet takes an elliptical path around the sun
Planets travel faster when they are close to the sun and slower when they are farther away from the sun
The amount of time needed for a planet to revolve around the sun is proportional to the the planet’s distance from the sun B C A

15. Precession
The direction this axis of a planet is pointing in will change, but the tilt will not change.
This will change the stars near the pole but will not change the seasons (as long as the angle of the tilt, 23.5 in the case of Earth, stays the same)

16. Nutation
Nutation happens when the axis of a planet starts to wobble (do the wobble!)
The angle of the axis will change during nutation ½ degree one direction or the other
Nutation happens over the course of 18 years
Nutation is a direct result of the moon (or moons) of a planet

17. Barycenter
A barycenter is the point between two objects where they balance each other (For example, the middle balancing point on a scale).
For example, the moon does not orbit the exact center of the Earth, but a point on a line between the Earth and the Moon approximately 1,710 km below the surface of the Earth, where their respective masses balance.
This is the point at which the Earth and Moon orbit as they travel around the Sun

18. Exit Ticket
Ready?
Questions?
Comments?
Doo-doo?

19. Exit Ticket: 11 points
Draw the shape of Earth’s orbit around the sun. (1 pt)
Explain why Earth takes the path you drew in question #1. (1 pt)
What is the angle of the Earth’s tilt on its axis? (1 pt)
Explain what Kepler’s law tells us. (1 pt)
Explain why the sun is always in motion. Use both the sun and Earth in your example. (1 pt)
Explain how Earth moves about the solar system (be sure to use rotate, revolve, nutation, precession, and barycenter, in your response). (5 pts)