1. Introduction to the Earth
Mrs. Marquis

2. The Solar System
• Our solar system is part of the milky way
galaxy
• Earth is one of 8 planets in our solar system
• The Sun is the central body of our solar
system
• The Earth and other planets orbit around the
sun in an elliptical

3. Our Solar System
• Image from www.aerospaceweb.org

4. The Solar System Cont…
• Milky Way Galaxy is one of at least
1,000,000,000 Galaxies in the universe.
• The universe is incredibly vast…beyond
most of our comprehension.
• Many believe the universe began with a
cosmic explosion “the big bang”
– 12-15 billion years ago

5. The Spheres
• Lithosphere
– Soil, rocks, landforms, etc.
• Atmosphere
– Air and water above surface of earth
• Hydrosphere
– The water in oceans, lakes, rivers, and aquifers
– 77% of earth is covered by water
• Biosphere
– All living things that occupy the earth
• plants & animals

6. The Spheres (picture from www.msu.edu)

7. Lithosphere
Picture from www.uwsp.edu

8. Atmosphere
• Picture from www.sponeil.org

9. Hydrosphere
• Picture from www.miami.edu

10. Biosphere
• Pictures from www.seashepard.com and www.dnr.wi.gov

11. Earth Movement
• ROTATION
– The Earth moves through space as it spins on
its axis like a top.
• Completes one rotation every 24hours.
• Spins from west to east.
• Sun appears to rise in the east and set in the west.

12. Rotation
• Image from www.berkely.edu

13. Earth Movement cont…
REVOLUTION
• The Earth takes 365 ¼ days to move around the sun
in nearly a circular path
– The Earth is tilted as it moves.
– The tilt means some places receive more direct
sunlight.
• The Tropic of Cancer and the Tropic of Capricorn (23
½ degrees) receive the most direct sunlight.

14. Revolution
Picture from www.education.arm.gov

15. Solstices
Solstices
• Summer solstice is around June 21
– the longest day in the Northern Hemisphere
– N of 66.5 degrees experience 24 hours of daylight (Arctic
Circle)
– S of 66.5 degrees S experience 24 hours of darkness
(Antarctic Circle)
– Noon rays of sun are perpendicular to Tropic of Cancer
• 23.5degrees N
• Winter solstice is December 21 in the Northern
Hemisphere

16. Equinoxes
• Equinoxes
• March 20 Vernal (spring) Equinox
• September 22 autumnal Equinox
• “equal day and nights”
– Sun’s rays strike the equator at noon creating a 90 degree
angle
• (See diagrams on page 18 of 10th edition)
*At all times the sun lights up about ½ of the earth

17. Standard Time
• At 1884 International Prime Meridian
Conference the world was divided into 24
standard time zones
– Each extended over 15 degrees longitude
– Greenwich (prime) meridian chosen as standard
for the system
– Greenwich Mean Time (GMT) now called
Universal Time Coordinated (UTC)

18. Standard Time Zones
• Picture from www.uwsp.edu

19. Standard Time-The U.S.
• Eastern Standard Time (UTC – 5)
• Central Standard Time (UTC-6)
• Mountain Standard Time (UTC-7)
• Pacific Standard Time (UTC-8)
• Alaska Standard Time (UTC-9)
• Hawaii Standard Time (UTC-10)

20. Us Time Zones

21. Day Light Savings Time
• Purpose was to conserve energy during
WWI
– Germans ordered clocks forward 1 hr
– Reduced energy use of citizens
• US began similar policy in 1918, not
everyone observed it
– Uniform Time Act forced all states to comply
except Hawaii and parts of Indiana and Arizona
• Many other nations have followed

22. Picture from www.lanl.gov