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Impact! PowerPoint PPT Presentation


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Impact!. Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green Bay. The Solar System. Nine Eight Planets Over 100,000 catalogued asteroids ???? Centaurs ???? KBO’s (including one disgruntled ex-planet) Millions of Comets. The Hazard. It’s all about Kinetic Energy

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Impact!

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Impact!

Steven Dutch,

Natural and Applied Sciences, University of Wisconsin - Green Bay


The Solar System

  • Nine Eight Planets

  • Over 100,000 catalogued asteroids

  • ???? Centaurs

  • ???? KBO’s (including one disgruntled ex-planet)

  • Millions of Comets


The Hazard

  • It’s all about Kinetic Energy

  • K = ½ mv2

  • 10 m block @ 30 km/sec = 100 Kt

  • Multiply size by 10, multiply K by 1000

  • Comets (large v) have more energy


Impacts on Earth


The Impact Process

  • Atmospheric Entry

  • Contact-Compression

  • Penetration – Transient Crater

  • Excavation

  • Collapse


Small Impacts Make Simple Pit Craters


Recent Impact – Meteor Crater


Medium Impacts Create Central-Peak Craters


How Central Peaks Form


Upheaval Dome, Utah


Schrodinger: A Peak-Ring Crater


Large Impacts Result in Multiple-Ring Basins


Comets and Planetary History

  • Superposition

  • Crater Saturation

  • Crater Degradation


Superposition


Crater Saturation


Crater Degradation


Recognizing Craters on Earth

  • Craters rapidly destroyed by erosion

  • Circular geologic structures

  • Impact melts

  • Impact breccias

  • Shock metamorphism

  • Shatter cones


Manicouagan, Quebec


Sudbury, An Ancient Impact Site


A Shatter Cone


Fallback Breccia


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


How Did The Moon Form?

  • Co-Creation

  • Fission

    • Moon should orbit in Earth’s equatorial plane

  • Capture

    • Can account for plane of Moon’s orbit

    • Very hard to do in reality

  • Collision

    • Requires no skill at all


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


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