1. Reasons for the Seasons

2. Reason #1 The Earth’s axis is tilted at a 23.5 degree angle.
**The Earth’s rotation on its axis causes day and night**

3. Reason #2
The Earth revolves around the sun (one full revolution takes 365 ¼ days), while maintaining it’s tilt, always pointed toward Polaris (also known as the North Star)

4. Reason #3 Different intensity of sunlight hitting the Earth
(direct vs. indirect sunlight)

5. Sunlight hits the Earth with different amounts of intensity depending on which hemisphere is pointed toward the sun.
Northern hemisphere pole tilted toward the sun  light is more direct and intense = summer
Summer in the northern hemisphere = winter in the southern hemisphere because the southern pole is tilted away from the sun: indirect rays hit the Earth here.
Intensity of the sun is consistent at the equator regardless of season.

6. THE SEASONS HAVE NOTHING TO DO WITH HOW CLOSE THE EARTH IS TO THE SUN!!!

7. Why is it light for longer periods in the summer?
It is light for longer periods in the summer because the sun is more direct.

8. Why does it get dark earlier in the winter?
It gets dark earlier in the winter because the suns rays are at more of an angle.

9. Draw a picture of the Earth and sun when it is summer in the northern hemisphere
Draw a picture of the Earth and sun when it is winter in the northern hemisphere

10. Solstice
The sun reaches its greatest distance north or south of the equator on these two days:
Around 6/21: summer solstice in N. hemisphere and winter solstice in S. hemisphere
Around 12/21: winter solstice in NH & summer solstice in SH

11. Draw a picture of where the Earth is during the summer solstice in the southern hemisphere
Draw a picture of where the Earth is during the winter solstice in the southern hemisphere

12. Equinox
Halfway between the solstices; neither pole is pointed toward or away from the sun.
Day & night are about 12 hours long everywhere on Earth (day time=night time)
Noon sun is directly overhead at the equator
Around 3/21: spring (vernal) equinox; marks beginning of spring in N.H
Around 9/21: autumnal equinox; marks the beginning of autumn in N.H

13. Draw a picture of where the Earth is during the autumnal equinox in the northern hemisphere
Draw a picture of where the Earth is during the vernal equinox in the northern hemisphere