1. Our Corner of the Universe 100 mil ly5 mil ly

2. Our Neighborhood

3. Earth’s rotation, orbit and the seasons  Only 50% of the Earth’s surface can be “lit” by the sun  Because the Earth’s axis is tilted the area covered by this 50% varies throughout the year

4. Most important variables  Earth’s orbit is 365.25 days long  Earth’s axis of rotation tilts 23.5° from the perpendicular These two variables account for the seasonal changes in weather patterns that we observe in a given year These two variables account for the seasonal changes in weather patterns that we observe in a given year

5. We have four seasons: why? The Earth’s axis of rotation is tilted at 23.5° from the perpendicular

7. Earth-Sun Relations

8. Latitude  Affects the amount of insolation received at the Earth’s surface  The subsolar point (at right angles to the plane of the ecliptic) receives most insolation Insolation decreases north and south of this point Insolation decreases north and south of this point  The subsolar point migrates from 23.5°N in the summer to 23.5°S in the winter

9. Subsolar point

10. The latitudinal zones

11. Perihelion vs Aphelion

12. MILANKOVITCH CYCLES - ACCOUNTS FOR PERIODIC GLACIATION OF EARTH

13. MILANKOVITCH CYCLES

16. THE NEXT ICE AGE? WHEN