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Meteors and Meteorites

Meteors and Meteorites. “Meteoroids” - still in space…. “Shooting Stars”. Size of a pea velocities of 10’s km/sec ~ 6/hour sporadic rate (any night). “Bolides” or “fireballs”. Sometimes seen in daytime. Sometimes break up. Meteor “train” can persist. If hit: “meteorites”.

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Meteors and Meteorites

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  1. Meteors and Meteorites

  2. “Meteoroids” - still in space…

  3. “Shooting Stars” • Size of a pea • velocities of 10’s km/sec • ~ 6/hour sporadic rate (any night)

  4. “Bolides” or “fireballs”

  5. Sometimes seen in daytime

  6. Sometimes break up

  7. Meteor “train” can persist

  8. If hit: “meteorites”

  9. Meteor showers occur when we cross paths of a broken up comet Here the “Persieds” named …

  10. … named for constellation containing the radiant point Leonids shown here or plotted…

  11. …plotted back to radiant in Leo

  12. Caused by perspective – the artist’s “vanishing point” Driving in snow

  13. Major showers Handout

  14. Leonids spectacular every 33 years • Due to lumpiness in distribution of old comet within orbit • This woodcut from 1833 – 100,000/hour • My first chance – 1966 • Most recent 2000-2002-who saw?

  15. Meteors better after midnight But…

  16. Meteorites: types Carbonaceous Iron-nickel Iron Stony

  17. Iron most commonly found but more stony meteorites more common!

  18. Widmanstatten patterns

  19. Stony meteorites – 93% of all meteorites

  20. Show chondrules (round stones) when cut and polished

  21. Stony-irons show a mix

  22. Carbonaceous chondrites • this at right from 1969 Allende’ fall in Mexico • Primordial in content • Contain volatiles • Organics • Radioactive nuclei – 26Al may be from supernova that sparked the formation of our solar system

  23. Model to explain the variety

  24. Barringer crater in Arizona 1.2 km diameter, 25,000 years ago, 11 km/s = 20 Mton bomb

  25. Drilling found the rock

  26. 41-mile diameter crater in Quebec

  27. Tunguska Heard for 1000 km. Small comet? What if had happened 60 – 70 years later?

  28. Walter and Luis Alvarez found iridium clay layer at Cretacous-Tertiary boundary (65My ago) Traced impact to …

  29. Chicxulub Impact structure • A bad day for dinosaurs • Expect such hits every ~ 8 million years • May find a kilometer within 10-20 years • Need to look for 100-m objects • Need a wakeup call?

  30. That’s all. Have a nice day!

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