1. Formation of The Earth

2. Composition of the Sun

3. The Most Unusual Element Administratium (Ad) No protons: Atomic Number Zero One neutron 27 Assistant neutrons 137 Deputy assistant neutrons 332 Associate neutrons Detectable indirectly: slows down all reactions it participates in

4. Composition of the Sun Abundance of Light Elements Rarity of Lithium, Beryllium, Boron Preference for Even Numbers Abundance peak at Iron, trailing off after

5. How Elements Form in Stars Sun: 4 H  He He + particle  Mass 5 – Unstable He + He  Mass 8 – Unstable He + He + He  C Add more He to make heavier elements End of the line is iron for energy production Atoms beyond Iron made in massive stars

6. What are Planets Made of? Same material as Sun Minus the elements that remain mostly in gases We find this pattern in a certain class of meteorites

7. Chondrites

8. Chondrite

9. The Earth’s Crust looks Very Different

10. Composition of the Crust

11. Hot or Cold? Up to 1940: Earth is hot inside, so must have formed hot 1940-1970: Earth need not have formed hot 1970-Earth did form hot after all

12. Hot Early Earth? Lord Kelvin, 1862: estimate age of Earth from cooling. – Earth’s heat is left over from its formation – Heat travels outward by conduction – Earth is not producing heat Only one problem (actually three): Every one of Kelvin’s assumptions was wrong

13. Three Images of Early Earth

14. Chesley Bonestell’s Classic Image

15. Nuclear Processes Radioactivity (Becquerel, 1896) Importance for Earth history: – Used for dating rocks – Explains sun’s energy output – Earth does produce heat

16. Maybe Earth Formed Cool? Planets formed by accretion of smaller bodies Each impact produces heat If rate is slow enough, heat can radiate away as fast as it is produced

17. Earth Formed Hot After All Apollo samples: Moon had “magma ocean” Better understanding of impact physics Role of mega-impacts Formation of core

18. Magma Ocean by Ron Hartmann

19. Craters and Planetary History Superposition Crater Saturation Crater Degradation

20. Superposition

21. Crater Saturation

22. Crater Degradation

23. Biggest and Oldest Crater on the Moon

24. Impact History Earliest records on Moon, Mars and Mercury: Intense Cratering As planets grow, their gravity increases. Impacts get more violent Debris from impacts buries hot rocks from earlier impacts Heat builds up Magma Ocean

25. Basalt and Anorthosite

26. How Do Planets Accrete? Tiny objects can be held together by welding, electrical forces, chemical interactions Big objects hang on to incoming material by gravity Things the size of a car are the mystery right now

27. Computer Studies Start with as many orbiting objects as your computer can handle Let them collide Don’t get 8-10 nice, regular planets Get 100’s of Moon and Mars-sized objects These collide to make bigger planets Violent beyond your wildest dreams

28. How Did the Moon Form? Co-Creation? Fission? Capture? 1985: Bill Kaufmann, Jay Melosh and others: Mega-Impact

29. Mega-Impacts: As Usual, Gary Larson Gets There First

30. Computer Simulations by H.J. Melosh (University of Arizona)

33. Formation of the Moon

35. View from the early Moon Earth would have been as hot as the Sun for 10,000 Years

36. Earth’s Atmospheres and Oceans Primordial from accretion Magma Ocean Mega-Impacts (1000 km +) – Magma Ocean – Vaporized Rock (100’s years) – Steam Smaller Impacts (100 km +) – Vaporized Rock (Years) – Steam (Boil off Oceans)

37. Earth Finally Settles Down Origin of Atmosphere and Oceans? – Outgassing? – Impacts of comets? Early Atmosphere Probably Mostly CO 2, and H 2 O

38. Bonestell: The Earth Cools

39. Bonestell: The Oceans Form

40. Hartmann: The First Moonrise

41. The Very Early Earth (Hadean) Intense cratering on Moon (and presumably Earth) ends about 4 billion years ago. Oldest earth material: 4 billion year old zircon from Australia. Oldest rocks: 3.9 billion years, NW Canada. Minnesota River Valley rocks: 3.1 billion years. Can’t say much about processes Liquid water from the git-go

42. The Faint Early Sun Sun 4 billion years ago was only 70% as bright as now. Would make average temperature of earth -15 F (-26 C) But earth has always had liquid water Must have had denser atmosphere, greater greenhouse effect.

43. The Archean 3.0 – 2.5 billion years ago About half of earth’s continental crust forms Granite, deep-water sediments and volcanic rocks, deep crustal rocks Were there mountains? Did Plate Tectonics exist?

44. Molasse, Switzerland

45. Molasse and the High Alps

46. Archean Granite

47. Archean Pillow Lava

48. Archean Iron Formation

49. 3.1 Billion Year Old Gneiss

50. Archean North America

51. Bear and Nain Provinces

52. Rae Block Collides

53. Penokean About to Begin

54. Penokean Orogeny and Churchill Collision

55. Wyoming Province Collision

56. Hearne Block Collides

57. Trans-Hudson Orogeny

58. Mazatzal Orogeny

59. Yavapai Orogeny

60. Midcontinent Rift Forms

61. Grenville Orogeny Complete

62. Present North America