1. Earth How We Know What We Know The Inside Volcanoes The Outside Drills
Gravity
Magnetic Fields
Earthquakes
The Outside
Rocks (free)
Maps
Many Satellites
Global Positioning

2. Some Earth Satellites ISS Aura ADEOS-2 Terra ICESat-2 GOES 13
Earth Observing Mission 2

3. Earth

4. Continental Plates – Global Positioning
Surface is moving
A few cm per year

5. The Earth – Continental Drift

6. The Earth – Deep Drilling
Greatest depth drilled = 12 km

7. The Earth – Volcanoes
Provide samples from shallow interior of Earth

8. The Earth – Volcanoes

9. The Earth – Clues to the Interior
Gravity measures mass of Earth
Magnetic fields from interior
Fluid Layer
Conductor (metal)
Motion (rotation)
Earthquakes!

10. Earthquakes
San Andreas Fault

11. Earthquakes
Different types of waves travel differently through the Earth
P-waves are pressure waves
Can travel through solids and liquids
S-waves are shear waves
Can travel through solids only
Surface waves travel only on the surface

12. Earth’s Interior Q. 29: Earth’s Magnetic Field The Crust
Thin layer of lightweight rocks
Rigid – can’t flow
The Mantle – largest part
Denser rocks
Plastic – can be deformed slowly
Flows over time
Cores
Mostly iron
Outer core – liquid
Inner core – solid
Q. 29: Earth’s Magnetic Field

13. Convection Heat inside Earth causes expansion
Lower density causes hot areas to rise
Like water in a pan
Plastic mantle can flow as well
Continents carried on top of flowing mantle
Rigid crust can’t flow - it breaks instead (sometimes)

14. Earth’s Magnetic Field
Outer core is liquid metal
Currents can flow in it
Rotation of Earth regenerates field
Tilted compared to rotation axis
Direction/strength changes over time
Charged particles from Sun deflected by our magnetic field
Solar wind on atmosphere creates Aurora Borealis and Australis

15. Earth’s Magnetic Field

16. Factors Causing Earth’s Surface Features
Moving plates
Mountains
Ocean Trenches
Continents
Subduction
Erosion
Rain
Wind
Volcanoes

17. Earth – Meteor Craters Q. 30: Earth’s Meteor Craters
Atmosphere blocks or slows all but the largest meteors
Only large meteors make it through
Erosion wipes out evidence of most of these
All but the largest get eliminated over time
In the long run, volcanism and subduction eliminate the rest
The oldest craters are all gone

18. Barringer Meteor Crater

19. Bosumtwi Crater

20. The Earth: Atmosphere Composition Nitrogen Oxygen
Moderates temperatures
Globally
Temporally

21. The Earth: Water
Earth is only place in Solar System with liquid water on the surface
Allows life to develop?

22. The Earth: Greenhouse Effect
Visible sunlight heats the surface of the Earth
Some reflected by clouds
Some reflected by Earth
Warm Earth reradiates infrared radiation
Penetrates most of atmosphere fine
Some is captured again
Since Earth is more efficient at transmitting visible than infrared, Earth is warmer than you would expect
The greenhouse effect

23. Greenhouse Gasses
Some gasses are better at transmitting visible than infrared
Water vapor (H2O) – Not very efficient, but there’s a lot of it
Carbon dioxide (CO2) – Very efficient, reasonably abundant
Methane (CH4) – Extremely efficient, but very little of it
Most energy production produces carbon dioxide
Coal – produces the most
Oil – produces a lot
Natural gas – produces some
Nuclear, Solar, wind, Geothermal, etc. – produces none

24. Life on Earth Q. 31: Life on Other Planets
Earth contains oxygen because of plants
Plants also absorb carbon dioxide
Killing plants warms the Earth
Q. 31: Life on Other Planets