1. Motions of the Solar System

2. Earth’s Motions Earth has Three Motions 1. Daily 2. Yearly 3. Cyclic

3. Earth’s Motions Rotation  Causes Day and Night  Two types of Day Sidereal Sidereal Time it takes for the Earth to make one Complete rotation Time it takes for the Earth to make one Complete rotation 23 hrs and 56 minutes23 hrs and 56 minutes Solar Solar Time it takes to go from one Noon to the NextTime it takes to go from one Noon to the Next 24 hours24 hours  Earth has a tilt of 23.5 Degrees One cause of the seasons One cause of the seasons

5. How Fast are We Moving?

6. Earth’s Motions Revolution  Earth’s Yearly Journey around the Sun  365 days  One Cause of the Seasons Changes the Amount of solar radiation reaching the earth Changes the Amount of solar radiation reaching the earth  Aphelion Furthest point away from the sun Furthest point away from the sun  Perihelion Closest point to the sun Closest point to the sun

7. Annual Motion of the Earth  Earth’s Annual Motion around the Sun is an ellipse  Ellipse An Elongated Closed Circle An Elongated Closed Circle Sun is not at Center Sun is not at Center

8. Earth’s Motions

9. Precession

10. The Cause of the Seasons

11. Sun Position Relative to Earth Event Degrees in Latitude DateSeason Vernal Equinox 0 or Equator March 21 st Spring Summer Solstice 23.5 0 N or Tropic of Cancer June 21 st Summer Autumnal Equinox 0 or Equator September 21 st Fall Winter Solstice 23.5 0 S or Tropic of Capricorn December 21 st Winter

13. No Tilt, No Seasons

14. Height of Sun in Sky

15. Angle of Insolation

17. Length of Day and Latitude

18. Latitude and Amt. of Solar Radiation