Energy

1. Energy • Drives earthquakes and volcanic eruptions • Concentrated at certain tectonic settings • Associated with the Earth’s formation

2. Driving Forces on and within the Earth?

3. Driving Forces within the Earth • Heat formation: • Impact of asteroids and comets in Earth’s early history • Decay of radioactive elements • Gravitational contraction • Differentiation into layers Artist Impression, NASA

4. Driving Forces on and within the Earth? • Earth’s internal heat • Flows within the mantle (largest volume of Earth) • Release in terms of volcanic activity and earthquakes • Long-term: continents, oceans and atmosphere • Movement of tectonic plates Greg Houseman, University of Leeds

5. Driving Forces on the Earth • Gravity: the attraction between bodies • Segregating elements within the Earth • Movement along the Earth’s surface • landslides • Movement within the Earth • Subducting oceanic slab moving into the mantle Landslide, China

6. Driving Forces on the Earth • The Sun • ¼ of the Sun’s energy reaches the Earth • Evaporation • Warming of atmosphere and hydrosphere • Weather: movement of air from warm to cooler areas

7. Formation of Solar System • What happened in the past and how is this currently reflected? • Gravitional force • Variations of temperatures • Rotation • Composition of material • Different states of matter

8. The Nebular Hypothesis • A nebula is formed from a collection of gases (98%) and dust (2%) • The mass rotates and is held together by gravity. The solar system formation

9. Where do we see this in our sky? • Third star down on Orion’s belt • Star nursery • 100 light years across (1 light year equals 6 trillion miles) • Reflection of dust and hydrogen

10. Orion Constellation • Winter sky constellation • Hunter in Greek mythology • New stars in several hundred million years

11. Nebula exists and through time: Contracts causing the nebula to increase temperature in center and increase speed of rotation Nebula: Step I

12. The Nebula collapses: step 2 • The collapsed mass forms a proto-sun and disc-shape rotating mass of gas and dust. • The Orion nebula contains about 153 visible protoplanetary disks • 2-17 times larger than our solar system

13. Rotation increases Temperature increases: 1,800,000 degrees Fahrenheit Fusion begins Protosun

14. Fusion • What does “to fuse” mean? • Remember, what is the composition of the nebula? • Look on the periodic table • What is the relation or difference between Hydrogen and Helium? • Can you predict what fuses?

15. Fusion • Hydrogen (1 proton) fuses with another Hydrogen (1 proton) = Helium (2 protons) • E = mc2 • E = energy • m= mass (very small) • c squared =speed of light (186,000 miles/second)

16. Step 3: Sun Forms • The disk is “cleared out” due to the immense amount of energy released. • Dust and gases cool, condense and accrete forming planetesimals. • Defined orbits around the sun

17. Earth’s internal heat from formation

18. Our Sun • Collapsed disk not shown • Sun is about 5 billion years old • 5 billion years until a red giant is formed

19. Step 4: Material Cools and Condenses; planet formation • Temperature differences with respect from the sun • Terrestrial planets (closer) • Jovian or gaseous planets (farther away)

20. Solar System • The first four planets are terrestrial (iron and silicate) • The last planets are composed of gases

21. Moon’s Formation 5:20 • A large size planet , thought to be the size of Mars, collided with Earth- 4.4 billion years ago • The debris formed the moon • The impact, set the Earth on its axis • 23 degrees

22. The Earth tilted on its axis in response to the collision

23. The Early Earth • Hot • Homogenous • Crust as we know it, not developed • 4.6 billion years ago • Melted again due to the collision of the Mars size planet

24. Transitional Earth • Segregation of elements by density • Iron moves to the center • Gravitational pull and rotation

25. Chemically distinct layers • Crust: oxygen and silicon (70%) • Mantle: iron, magnesium, lower % Si, O • Core: iron and nickel

26. Inner core: solid Outer core: liquid Mantle: capable of flow Asthenosphere: acts like a hot plastic Lithosphere: rigid Physically Distinct Layers

27. Lithosphere • Rigid layer that lies between the surface and 60-100 miles • “Floats” on the asthenosphere • The tectonic plates are composed of lithosphere Lithosphere Contains crust and upper mantle

28. Continental Crust • Less dense • Higher % of silicon and oxygen • Lower % of iron and magnesium • Thicker (15-25 miles) • 30 % of Earth’s surface

29. Oceanic Crust • More dense • Higher % of iron and magnesium • Lower % of silicon and oxygen • Thinner (5-7 miles) • 70 % of Earth’s surface

30. Asthenosphere • Relatively soft layer capable of flow that lies below a depth of 60-100 miles (upper mantle) Dr. Railsback, University of Georgia

31. The Mantle • Largest portion of the Earth • Very rich in iron and magnesium • Very poor in silicon and oxygen • The mantle is solid but because of high temperatures and pressures, it is soft enough to flow • The asthenosphere is part of the upper mantle

32. The Core • Outer core-liquid which can flow and generates the Earth’s magnetic field • Inner core- solid and rotates faster than the Earth • Mostly iron, some nickel Complex fields in the core contribute to the dipole field at the surface (UC Berkeley)

33. The magnetic field protects the Earth from solar radiation

34. External Source of Earth’s Water • The collision of comets with the Earth’s surface • As the ice hits the warm Earth, the ice melts to water • Gravity holds the water to the surface Haley’s comet contains ices and dust. The tail is created by ice to sublimate to steam.

35. Internal Source of Earth’s Water • Water vapor is released during volcanism • Cooling of the hot Earth involved intense volcanism • Water condenses

36. Formation of Atmosphere • Gas is expelled from magma during volcanic eruptions • Nitrogen, carbon dioxide, hydrogen, sulfur dioxide and water • Early Earth’s atmosphere did not contain which gas? Why?

37. History of the Earth • 4.6 billion years old • 4.4 bya, formation of moon • 3.9 bya, oldest rock (sedimentary rock) • sedimentary rocks are made-up of fragments of preexisting rocks • Sediments are carried and deposited by water and wind • implies the existence of weather and water • 4.1 bya, age of particles within the sedimentary rock Early Earth

38. Fossil Worm, Cambrian History of the Earth Sponge • 3.5 bya, first bacteria • 3.2 bya, algae (product?) • plants • photosynthesis, by-product is oxygen • worms and jelly fish • 500 million years ago, Cambrian (life) explosion: marine fauna; modern phyla: sponges, mollusks (clams and snails), echinoderms (sea urchins and stars), anthropoda -trilobites(crabs, lobsters) Trilobite

39. Earth as an evolving system • Creation and early Earth • Earth’s chemically and physically distinct layers • Atmosphere (air) • Hydrosphere (water) • Biosphere (plants and animals)

40. Summary • The Nebular Hypothesis • Earth’s heat sources • Radioactive decay • Initial heat produced by collision of other objects • Moon, water and gas formation • Earth’s layers, differences and locations • Importance of gravitational pull Think Quest