1. Rotation & Revolution

2. Astronomy The study of the moon, stars and other objects in space.

3. Axis The imaginary line that passes through the Earth’s center and the North and South poles. 23.5° angle/tilt

4. Rotation Earth’s rotation, or spin, on its axis (23.5 ) causes day or night.

5. Night & Day The Earth rotates on it’s axis every 23hrs and 56 mins (almost 24 hrs) The sun shines on only ½ of the Earth at a time. –½ of the Earth is experiencing night time. While the other ½ is in daylight!

6. What Is Rotation? For every complete rotation one day has passed. Earth spins counter- clockwise.

7. Sunset from space

9. Orbit Orbit –Earth’s path as it revolves around the sun. –Earth’s orbit is not circular. It revolves in an oval shape called elliptical

10. Revolution or orbit –The time it takes for the earth to make one complete revolution around the sun is called a year.

11. One Revolution = 365.25 days or One Year - This is why we have a leap year every 4 years!

12. Revolution Causes changes of the seasons?

14. Seasons are caused by 1. Earth’s revolution around the Sun 2. the unchanging tilt of the Earth’s axis. Common Misunderstandings: Earth’s changing distance to the Sun does not cause seasons!

15. The north pole tilts towards the sun I t is Summer time in countries in the Northern Hemisphere. It is Winter time in countries in the Southern Hemisphere.

18. Shadows and Seasons Summer –Sun is more overhead and “Direct” which causes more of a direct (strong) path for radiation.

19. Direct rays on a small area are strong and cause summer seasons. Short Shadows

20. Shadows and Seasons Winter –Sun is more slanted and “Indirect” which causes a less direct (weaker) path for radiation.

21. Slanting rays focusing on a large area are weaker and cause winter seasons. Longer Shadows

22. One more time… We have seasons because: 1. The tilt of the Earth’s axis 2. The revolution of Earth around the Sun.

27. As you are annotating…answer the following 1.What does the orbit of the Earth look like? (Perfect circle, “egg shaped” etc.) 2.Where are the ends of the Earth’s axis? 3.Why isn’t Earth’s orbit in a straight line? 4.About what angle is Earth tilted?