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Chapter 11, 12,13

Chapter 11, 12,13. Comets, Asteroids, Meteors. Minor Body Comparisons. Property ___Asteroids _________ Comets. Orbit Shape Circular to Highly elliptical elliptical. Size 0.5 km to 625 km Nucleus 1 to 10 km.

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Chapter 11, 12,13

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  1. Chapter 11, 12,13 Comets, Asteroids, Meteors

  2. Minor Body Comparisons Property ___Asteroids _________ Comets Orbit Shape Circular to Highly elliptical elliptical Size 0.5 km to 625 km Nucleus 1 to 10 km Composition Iron or Rocky Ice and Rock Named? Named by their Named after their discoverers discoverers

  3. Asteroids • a.k.a Minor Planets • Belt Asteroids - are those found between the orbits of Mars and Jupiter. • Trojan Asteroids - share Jupiter's orbit about the Sun • Apollo Asteroids – have orbits that cross Earth’s orbit • NEO – Near Earth Objects

  4. Kirkwood Gaps

  5. Asteroids • The are empty regions in the asteroid belt called Kirkwood Gaps. • (Created by Jupiter’s gravity)

  6. Blink Comparison Minor Planet

  7. Asteroids • The asteroids are probably fragments of planetesimals, the bodies from which planets were built. • Over 100 “new” asteroids are discovered every year. • There are over 7,000 known asteroids. • Examples: • Ceres (diameter = 625 miles) • Gaspra (3 by 12 miles) • Toutatis (0.5 by 2 miles)

  8. Toutatis • A strange binary asteroid imaged with radar from Earth. Goldstone Deep Space Communications Complex 2.5 and 1.6 miles

  9. 12 miles Gaspra • The first asteroid to be imaged at close range. • This was done with the Galileo spacecraft.

  10. Satellite! Ida • The second asteroid imaged with the Galileo spacecraft. • It has a moon! 36 x 14 miles

  11. Methilde • The spacecraft NEAR made a flyby of Mathilde on June 27, 1997.

  12. Vesta • Vesta has been studied recently with Hubble Space Telescope. Diameter = 165 miles

  13. Comets • There are two reservoirs for comets • Kuiper Belt • Oort Cloud • The solar wind produces two tails on comets: the dust tail and the ion tail. • Examples: • Halley's Comet • Hale-Bopp • Shoemaker-Levy 9

  14. The Oort Cloud

  15. Structure of a Comet Ion Tail Dust Tail Coma To Sun

  16. Comet Halley • It orbits the Sun every 76 years. • It was imaged in 1986 at close range by Giotto, a European satellite.

  17. Comet Halley 1910 • Pope Callixtus III excommunicated Halley's Comet in 1456 • In 1910, charlatans sold "comet pills"

  18. Comet Nucleus

  19. Hyakutake

  20. Hale-Bopp

  21. Comet West

  22. Comet Shoemaker-Levy 9

  23. Comet Shoemaker-Levy 9

  24. The End.

  25. Comet Shoemaker-Levy 9 • Was shatter by Jupiter’s gravity in 1992. • All pieces hit Jupiter in the summer of 1994 leaving dark impact scars.

  26. Meteors • meteoroid- small debris moving though space • meteorite - space debris found on Earth • Types • iron meteorites • chondritic meteorites

  27. Iron Meteorites Chondritic Meteorites

  28. Meteors • Sporadic Meteor • Random meteors with various compositions • Bolides • Leave trails (trains) that last for a few minutes • Sometimes make noise • Fireball • Sometimes take over half a minute to cross the sky • Sometimes have magnitudes brighter than Venus

  29. Meteors • How can you determine the composition of a meteor? • Take its spectra. • How can you tell how high it vaporizes? • Triangulation from two observers.

  30. Irons Stony-Irons Carbonaceous Chondrite Chondrites Achondrite Sporadic Meteors

  31. Meteors • meteor • a.k.a. “shooting star” • A small bit of rock that is heated by friction in the Earth’s atmosphere and gives off light • meteor shower • Results from the Earth passing though a comet's path • Can result in 100’s of meteors per minute • Are named after the radiant constellation

  32. Meteor Shower

  33. The 1833 storm

  34. The Cause of Meteor Showers P55/Tempel-Tuttle

  35. Earth Impacts and Near Misses • Arizona Meteor Crater • measures 1 mile across • from an impact 50,000 years ago • by a 50 meter meteoroid

  36. Tunguska Event • in 1908 • an asteroid broke up in our atmosphere • leveled trees for some 30 kilometers

  37. Chicxulub Event /cheek-shoo-loob/ • 65,000,000 years ago • 10 kilometer asteroid • is thought to have caused a mass extinction of dinosaurs

  38. How are asteroids and comets discovered? • Two pictures are taken of the same region of the sky at different times. • If any object in the pictures has moved then it could be… • an asteroid • or comet • or a planet • or a UFO.

  39. How Much Damage?

  40. The End... Live long and prosper.

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