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

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

Earth

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

The Earth – Continental Drift

The Earth – Deep Drilling Greatest depth drilled = 12 km

The Earth – Volcanoes Provide samples from shallow interior of Earth

The Earth – Volcanoes

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

Earthquakes San Andreas Fault

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

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

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)

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

Earth’s Magnetic Field

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

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

Barringer Meteor Crater

Bosumtwi Crater

The Earth: Atmosphere Composition Nitrogen Oxygen Moderates temperatures Globally Temporally

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

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

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

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