The document describes the four major spheres that make up Earth's system: the lithosphere (solid land and crust), hydrosphere (water), atmosphere (air), and biosphere (living things). It provides details on the characteristics and components of each sphere. Additionally, it discusses Earth's basic facts, motions of revolution and rotation, how seasons are caused by the tilt of Earth's axis and orbit around the sun, and defines solstices and equinoxes as the astronomical start of each season.

1. The Planet Earth: Its Motions and Seasons Chapter 1

7. FACTS ABOUT THE EARTH Average Distance from the Sun 92,955,820 miles Equatorial Circumference 24,901 miles Sidereal Rotation Period (Length of Day) 23.934 hours Sidereal Orbit Period (Length of Year) 365.24 Earth days Mean Orbit Velocity 66,629 mph Equatorial Inclination to Orbit 23.45 degrees Volume 259,900,000 mi3 Mass 5.9737 x 1024 kg Density 5.515 g/cm3

8. Perihelion/Aphelion

12. Seasons of the Earth

13. Earth at Winter Solstice

14. Earth at Summer Solstice

15. Why do we have seasons?

16. The Winter & Summer Sun

18. Seasons in the Northern & Southern Hemisphere

21. Summary

22. End of Presentation Exam next meeting….