1. Inside the Earth
r = 3,959 mi

2. As the Earth cooled…
heavier materials sank towards the center of the Earth and lighter materials surfaced to the top. Density = the degree of compactness of a substance = (mass / volume) = kg/m3

3. How do we know about the layers of the earth?
Scientists can tell by observing the seismic waves that are recorded all over the surface of the earth from distant earthquakes. The seismic waves are reflected (bounced off) layers of different density, and they are refracted (bent) when they enter layers of different density.
These are waves of energy that travel through Earth, and they move similarly to other types of waves, like sound waves, light waves, and water waves.

4. Earth’s Interior
Earth’s interior is divided into layers: the crust, mantle, & core, based on composition. Although the Earth’s crust seem stable, the extreme heat of the Earth’s interior causes changes that slowly reshape the surface.

5. In addition to compositional layering, other changes occur within the earth. Tare changes in physical properties such as rock strength and solid versus liquid.

6. The Crust
Outermost layer of earth made of rock that forms earth’s outer skin
5 to 100 km thick, average thickness is 35 km
thinnest layer
less than 1% of Earth’s mass
Composition of crust: oxygen, silicon, aluminum, calcium, iron, sodium, potassium, magnesium

7. The Crust Oceanic Crust Continental Crust crust beneath the oceans
consist mainly of dense rock (basalt - dark in color)
5-8 km thick
Continental Crust
crust that forms the continents
consist mainly of less dense rock (granite - lighter in color)
30 km average thickness

8. Crust to Mantle
The upper part of the mantle and the crust together form a rigid layer called the lithosphere.
Lithos is greek for stone, 100 km thick
made of pieces called tectonic plates
Upper Mantle

9. Tectonic Plates
The tectonic plates are pieces of the lithosphere that fit like pieces of a jigsaw puzzle and move on top of the asthenosphere
May Consist of both Continental and Oceanic Crust

10. Major tectonic plates:
Pacific plate North American plate Cocos plate Nazca plate Antarctic Plate
South American Plate Eurasian Plate Indian Plate Australian Plate

11. Crust to Mantle
The asthenosphere is a soft layer of the mantle on which pieces of the lithosphere move
asthenes is Greek for soft or weak
material is like warm tar and can flow slowly
The rigid crust and lithosphere float on the hot, plastic material of the asthenosphere.
made of solid rock

12. The Mantle layer of rock between crust and core
Hot, slow-flowing, solid rock
2900km thick, 67% of Earth’s mass
Composition - silicon, oxygen, iron and magnesium
physical conditions in mantle change because pressure and temperature increase with depth
temp ranges from 870 ºC to 2,200ºC

13. Lithosphere -> Asthenosphere -> Mesosphere
The innermost physical layer of the mantle.
Rock in this layer flow more slowly than in the asthenosphere.
Highly compressed rock that it has considerable strength even though the temperature is very high.
Exists within the mantle from a depth of about 350 km to the core-mantle boundary (2,883 km)

14. Convection Currents inside the Mantle
Hot columns of mantle material rise slowly through the asthenosphere
Convection currents occur when a heated fluid expands, becoming less dense, and rises. The fluid then cools and contracts, becoming more dense, and sinks.

15. Inside of the Earth, magma is heated near the core, rises toward the crust, then cools and sinks back toward the core. It is thought that this motion is responsible for the movement of the Earth's crust.
Heat generated from the radioactive decay of elements deep in the interior of the Earth creates magma (molten rock) in the aesthenosphere.

16. two images of mantle convection

17. The Core Innermost layer of the Earth
6800 km in diameter (3,400 km from outside edge of core to center of core)
1/3 of Earth’s mass, 15% of its volume
Temperature ranges from 2,000 ºC to 5,000ºC
Consist of 2 parts; Inner Core and Outer Core

18. The Outer Core
layer of molten metal (iron and nickel) beneath the mantle
LIQUID
surrounds the inner core
2,200 km thick

19. The Inner Core
dense ball of solid metal (iron w/ some nickel and others)
extreme pressure from layers above
1200 km, from outside edge of inner core to center
70% as wide as the moon.
The difference between the inner and outer cores is not one of the composition.
Instead, the difference lies in the physical states of the two: one is a solid, the other is a liquid.

20. Ionosphere
The ionosphere is a shell of electrons and electrically charged atoms and molecules that surrounds the Earth, stretching from a height of about 50 km (31 mi) to more than 1,000 km (620 mi). It exists primarily due to ultraviolet radiation from the Sun.
Ionization depends primarily on the Sun and its activity. The amount of ionization in the ionosphere varies greatly with the amount of radiation received from the Sun.
The start of Magnetosphere

21. Earth’s Magnetic Field
Earth's magnetic field comes from the outer core's ocean of iron, which is an electrically conducting fluid in constant motion that causes convection currents.
The inner core spins inside the Earth at a slightly faster rate than the rest of the planet
This movement creates the Earth’s magnetic field
The magnetic field waxes and wanes, the poles drift and, occasionally, flip.

22. Earth’s Magnetic Field
The earth acts as a giant bar magnet
Earth’s magnetic fields have reversed more than 177 times in the last 85 million years
Extends from Earth’s interior out into space, where it meets the colar wind, a stream of charged particles emanating from the Sun

23. Earth’s Magnetic Field
The solar wind exerts a pressure, and if it could reach Earth's atmosphere it would erode it. However, it is kept away by the pressure of the Earth's magnetic field.
As well as deflecting the solar wind, the Earth's magnetic field deflects cosmic rays, high-energy charged particles that are mostly from outside the Solar system.
Some of the charged particles do get into the magnetosphere.

24. Earth’s Magnetosphere
The pressure of the solar wind on Earth’s magnetic field compresses the field on the dayside of Earth and stretches the field into a long tail on the nightside.

25. AURORAS

26. AURORAS
Auroras are produced when the magnetosphere is sufficiently disturbed by the solar wind that the trajectories of charged particles in both the solar wind and magnetosphere, mainly in the form of electrons and protons, precipitate them into the upper atmosphere (thermosphere/exosphere) due to Earth's magnetic field, where their energy is lost.

28. The End