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A Short Look at Earth History

A Short Look at Earth History . Formation of Universe: 13-20 billion years Big Bang Theory Formation of Galaxy: 11 billion Years Formation of Solar System: 4.6 billion years Probably takes 10-100 million years for planets to form . Formation of UNIVERSE. BIG BANG THEORY.

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A Short Look at Earth History

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  1. A Short Look at Earth History

  2. Formation of Universe: 13-20 billion years • Big Bang Theory • Formation of Galaxy: 11 billion Years • Formation of Solar System: 4.6 billion years • Probably takes 10-100 million years for planets to form Formation of UNIVERSE

  3. BIG BANG THEORY

  4. FORMATION OF SOLAR SYSTEM

  5. Planets made of same material as Sun, minus elements that remain mostly in gases Inner Rocky Planets: iron and magnesium silicates Outer gas giants and moons: water ice If a protoplanet gets big enough, it can hold everything (Jupiter, Saturn) Very far from sun: methane, ammonia, nitrogen ice Formation of SOLAR SYSTEM

  6. Over 970 (973 as of 9/14/13)extrasolar planets known • 262 may be habitable planets • Most known are Jupiter-size planets, larger and easier seen • Super-Earths actually outnumber giant planets Our Solar System May Not Be Typical OR IS IT TYPICAL?

  7. THE MILKY WAY

  8. Planets formed by accretion of smaller objects = impact Very tiny objects hold together by atomic forces Objects kilometers across hold together by gravity How do objects the size of a refrigerator hold together? As planets get bigger, gravity gets stronger, impacts get more violent Big impacts throw out ejecta, trap heat Magma ocean Formation of core early in earth history as iron sinks Formation of Earth

  9. Formation of Earth

  10. It's very hard to account for the Moon: • Very big compared to its parent planet • Orbits nearly in plane of earth's orbit, not over equator. • Co-creation with Earth? • Fission? • Capture? Formation of Moon

  11. Over 4 billion years ago Can explain why moon orbits in earth's orbital plane Can explain why moon's composition differs from earth Models of solar system evolution suggest that last stage is mega-collisions Impact would have melted most of earth and moon Earth would have been incandescent for about 10,000 years Collision

  12. Collision

  13. May have been several moon-forming events • 1000-km impactors can melt crust • 100-km impactors create temporary atmosphere of vaporized rock, vaporize oceans • Life not possible until large impacts cease • To have life on Earth, we need Jupiter? • Sweeps up debris and reduces impacts • Stabilizes orbits of other planets • To have life on Earth, we need Moon? • Stabilizes changes in earth's axis tilt Unstable Early Earth

  14. GEOLOGIC TIME SCALE

  15. Oldest existing earth materials: 4.1 billion years old Oldest rocks: 3.9 billion years old Oxygen-poor atmosphere (present oxygen is created by life) Faint Early Sun: perhaps 30% less bright Evidence for liquid water from very early on Conditions on Early Earth

  16. Earth the Biography: Origin of the Oceans ORIGIN OF THE OCEANS

  17. Oxygen levels in atmosphere • Plants release waste oxygen • Eventually organisms developed a way to utilize oxygen • Sex: Who Needs It? • We are a team: Mitochondria • Snowball Earth: what survived and how? • Cambrian "Explosion" Major Events in the History of Life

  18. SNOWBALL EARTH

  19. CAMBRIAN EXPLOSION

  20. Mass Extinctions

  21. Climate Change Disease Mountain-building Sea Level Change Competing Organisms Over-specialization Volcanism Meteor Impact Humans Causes ?

  22. The Early Earth and Plate Tectonics Earth History

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