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Earth and Other Planets

Earth and Other Planets. 3 November 2015 Chapter 16. Great Idea: Earth, one of the planets that orbit the Sun, formed 4.5 billion years ago from a great cloud of dust. Chapter Outline. The Formation of the Solar System Exploring the Solar System The Earth.

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Earth and Other Planets

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  1. Earth and Other Planets 3 November 2015 Chapter 16 Great Idea: Earth, one of the planets that orbit the Sun, formed 4.5 billion years ago from a great cloud of dust.

  2. Chapter Outline • The Formation of the Solar System • Exploring the Solar System • The Earth

  3. The Formation of the Solar System

  4. Clues to the Origin of the Solar System • Solar system • Objects gravitationally bound to Sun • Deduction of origin • Observations • Earth • Space

  5. Clue #1: Planetary Orbits • Features of solar system • All planets orbit in same direction • Orbits in same plane • Most rotate in direction of orbit

  6. Clue #2: Distribution of Mass • Most material within Sun • Two types of planets • Terrestrial planets • Jovian planets • Other objects • Moons, asteroids, comets

  7. The Nebular Hypothesis • Nebular Hypothesis • Cloud of dust and gas • 99% H and He • Collapse of nebula • Planetary orbits • Clumping of matter • Planetesimals • Temperature

  8. Basic Planet Categories • Terrestrial planets • Mercury • Venus • Earth • Mars • Jovian planets • Jupiter • Saturn • Uranus • Neptune

  9. Some Conclusions • Planets formed at same time as Sun • Planetary and satellite/ring systems are similar to remnants of dusty disks such as that seen about stars being born • Planet composition dependent upon where it formed in solar system

  10. Nebular Condensation (protoplanet) Model • Most remnant heat from collapse retained near center • After sun ignites, remaining dust reaches an equilibrium temperature • Different densities of the planets are explained by condensation temperatures • Nebular dust temperature increases to center of nebula

  11. Nebular Condensation Physics • Energy absorbed per unit area from Sun = energy emitted as thermal radiator • Solar Flux = Lum (Sun) / 4 x distance2 • Flux emitted = constant x T4 [Stefan-Boltzmann] • Concluding from above yields T = constant / distance0.5

  12. Nebular Condensation Chemistry

  13. Nebular Condensation Summary • Solid Particles collide, stick together, sink toward center • Terrestrials -> rocky • Jovians -> rocky core + ices + light gases • Coolest, most massive collect H and He • More collisions -> heating and differentiating of interior • Remnants flushed by solar wind • Evolution of atmospheres

  14. Pictorial View of Origins

  15. Pictorial View Continued

  16. HST Pictorial Evidence

  17. HST Pictorial Evidence

  18. The Formation of Earth • Planetesimals • Combined (accretion) to form earth • Great bombardment • Meteors • Growth of planet • 20 metric tons per day

  19. Differentiation • Differentiation • Heat from collisions • Dense material sank to center • Lighter material rose to surface • Structure • Core • Mantle • Crust

  20. Crust and Us

  21. Earth’s Interior -How We Know It

  22. The Formation of the Moon • Large object (asteroid close to size of Mars) impacted earth • Parts of mantle blown into orbit • Moon formed from this material

  23. Planetary Idiosyncracies • Cratering • Mercury, Mars, Moon • Few on Earth • weathering • Rotation • Venus • Earth’s axis • Uranus

  24. The Evolution of Planetary Atmospheres • Earth’s atmosphere • Early • Outgassing • Atmosphere was N2, CO2, H2, & H2O • Gravitational escape • Living organisms

  25. Exploring the Solar System

  26. The Inner Solar System • Mercury, Venus, Mars • Mercury and Venus too hot for life • Mars Exploration • Multiple missions • Found evidence of water

  27. The Outer Solar System • Jupiter, Saturn, Uranus, Neptune • Layered structure • No solid surface • Jupiter • Comet Shoemaker-Levy • Galileo spacecraft • Saturn • Cassini spacecraft

  28. Outer Solar System II

  29. Jupiter’s Moons • Io, Europa, Ganymede, Callisto and 63 others known • Saturn’s Moons • Titan, Mimas, Hyperion and about 59 (61?) others • Rings • Ice and rock - more ice in Saturn’s rings Moons and Rings

  30. Dwarf Planet Pluto Surprises • It has moons • Original moon discovered 1978 • Charon (KAIR’ en) • Now more • 2005 discovery of 2 additional moons • Named Nix and Hydra • 2011 #4 is P4 (Kerberos) • July 7, 2012 #5 is P5 (Styx)

  31. Pluto’s Interior to SurfaceOld -> New Model • Model 1 • partially hydrated rock core • water ice layer II • predominant water ice layer I • Model 2 • partially hydrated rock core • organics layer • predominantly water ice layer

  32. The Launch of New Horizons Pluto Mission 17 Jan 2006 http://www.youtube.com/watch?v=KNJNaIoa5Hk

  33. Io’s Volcanoes from New Horizons

  34. Pluto

  35. Pluto’s Methane (frozen)

  36. Charon

  37. Pluto

  38. Pluto Atmosphere Detection

  39. Pluto and Charon

  40. Carbon Monoxide (Frozen)

  41. Solar Wind at Pluto

  42. Pluto “Heart” Region

  43. Pluto Mountain Range

  44. Nix and Hydra

  45. Pluto, True Color

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