1. Class 22: Space Junk (I)

2. Today’s topics: Asteroids Meteor-stuff Comets Class Updates Reading: 23.10 Lecture schedule update Homework & Exams returned

3. Asteroids Ida Gaspra Mathilde

4. Asteroid Locations

5. NEAs This Week http://neo.jpl.nasa.gov/ca/

6. A Bad Day…. 65 Million Years Ago Chicxulub

7. Asteroid Shapes & Sizes Mars

8. Asteroid Distances

9. Mini Moons of Asteroids small moon (1.5 km) Ida (100 km)

10. Asteroid Mission: NEAR Eros gravity close-up image

11. Eros Up Close

12. Upcoming Mission: DAWN Ceres Vesta

13. Meteor-stuff

14. Peekskill, NY August 1992 Incoming Debris

15. Definitions

16. Suppose that you are hiking along the icy banks of an Antarctic glacier and you stumble upon a very odd looking rock, which you later confirm to be a chunk of an asteroid that fell to Earth. a.Comet b.Meteoroid c.Meteor d.Meteorite Which of these is the proper scientific name of your discovery? Challenge Question

17. Meteor Showers Leonids, 11/2001Perseids, 8/2004

18. Earth’s largest meteorite….thus far Hoba Meteorite Namibia66-110 tons

19. Moon (meteor showers only) Mars Asteroid Vesta Origins & Ages of Meteors

20. Stony-Iron (2% falls, 8% finds) – asteroid core/mantle? Compositions (glassy beads, grains)(carbon, volatiles) Stones (92% falls, 26% finds) – rocky material (silicates) – ancient solar system – Carbonaceous chondrites Irons (6% falls, 66% finds) – like Earth core (melting) – debris asteroid core?

21. Bill Cassidy Where are meteorites found?

22. Meteor Crater Northern Arizona

23. Wolfe Creek, Australia Manicouagan, Quebec, Canada Clearwater Lakes, Quebec, Canada Gosses Bluff, Nor. Territory, Australia More Terrestrial Craters

24. Donahue meteorite Peekskil Chevy Human strike: Annie Hodges; Sylacauga, AL; bruised; 11/30/54 Animal strike: Dog; Nakhla, Egypt; 6/24/11 Structures: Donahue home; Wethersfield, CT; 11/8/82 Chevrolet; Peekskil, NY; 8/9/92 Hits & Misses

25. Comets May 7, 2004

26. Anatomy of a Comet Head Tail Gas Tail Comet West

27. nucleus Nucleus: Comet Head nucleus surface coma

28. Nucleus: Comet Wild 2

29. Comet Tails

30. Sunlight = Tails (movie)

31. Where does gas tail point?

32. Where do comets originate? (I) Sedna Halley’s Comet

33. Where do comets originate? (II) Comet Hyakatuke Comet Hale Bopp

34. Comet Shoemaker-Levy 9

35. 1 2 3 Which is which? a. (1) comet; (2) meteor; (3) comet b. (1) asteroid; (2) meteor; (3) comet c. (1) comet; (2) asteroid; (3) meteor d. (1) meteor; (2) asteroid; (3) comet Review

36. On the morning of June 20, 1908 witnesses described a brilliant fireball, brighter than the Sun, streak across the sky. Still de- scending, it exploded with a blinding flash & an intense pulse of heat. The blast was heard up to 1000 km away; the resulting pulse of air pressure circled Earth twice. 1000s of tons of a powdery material resembling carbonaceous chondrites were later found scattered in the soil. What do you think was the likely source of the Tunguska event? Trees flattened out to 30 km Tunguska, Russia Challenge Question