1. MAPPING THE EARTH

2. What do these have in common?

3. Model Representation of something else Examples?
Globe, equation, graph, chart, map
Why?
Earth, universe are too big. Time is too long.

4. True Shape of the Earth Slightly Oblate sphere Flattened at poles
Bulges at
equator

5. Circumference at Poles:
40,008 km
Circumference at Equator:
40,076 km

6. WHY?
Earth rotates and the centrifugal force when it spins causes it to bulge at the equator.
Think of a little girl in a dress that twirls around. The dress flares out.
Or think of the force that pulls you out when on a merry-go-round!

7. EVIDENCE THAT THE EARTH IS ROUND

8. 1. Observations of ships on the Horizon

9. 2. Lunar Eclipse - Shadow of the earth on the moon is curved

10. 3. Altitude of Polaris
More on that later!!!!

11. 4. Best Evidence that Earth is Round
Pictures from outer space

12. EARTH’S SPHERES

13. Atmosphere - Envelope of gases surrounding the earth
Made of gases so least dense sphere, 1.3 x 10-3 g/cm3
Atmosphere
ESRT Page 14

15. Most dense sphere, 2.8 – 3.0 g/cm3
- Earth’s solid outer layer, “shell of the earth”, crust and upper solid part of the mantle
lithosphere
Approximately 100 km thick
Most dense sphere, 2.8 – 3.0 g/cm3
ESRT Page 10

17. Hydrosphere - Layer of liquid water that covers the earth
70% of earth’s surface
ESRT Page 1
Hydrosphere

19. Biosphere
The portion of the earth and its atmosphere that can support life.

20. Atmosphere
Hydrosphere
Lithosphere