1. Class 9: Icy Moons and Space Junk

2. Today’s topics: Galilean moons: Io, Europa, Ganymede, Callisto Saturn’s moon: Titan Class Updates Reading: 23.4-23.5, 23.7 Homework 4 assigned, due next Monday Midterm next Monday, April 18th Midterm review material posted on website Class 9: Icy Moons and Space Junk Asteroids Meteor-stuff Comets

3. Moon Size Compariso n. Io Europa Ganymede Callisto Titan Triton Charon

4. Jovian Moons = Galilean Moons

5. Orbit Diameter Mass Density (days) (Moon = 1) (Moon=1)(g/cm 3 ) Io1.81.01.23.5 Europa3.60.90.73.0 Ganymede7.21.52.01.9 Callisto16.71.41.51.8 Jovian Moon Comparison

6. Exploration Galileo’s notes Voyager 1 Galileo spacecraft

7. Internal Structure

8. Tidal Heating

9. Io

10. Tides on Io

11. Plumes on Io: How?

12. Volcanism & Impact Craters on Io

13. Europa

14. Brittle Surface Ice Europa’s Subsurface Ocean? Liquid? Brittle Surface Ice Warm, Convecting Ice?

15. Evidence for Europa’s Subsurface Ocean

16. Europa’s Surface Features Ridges Spots Icebergs Craters Bright Bands

17. Ganymede

18. Ganymede’s Grooved Surface

19. Ganymede’s Magnetic Field: (Geologically Alive?)

20. Callisto

21. Callisto: Geologically Dead

22. Callisto’s Icy, Cratered Surface

23. How many? Saturn’s Moons most geologically dead cracks: Tethys, Mimas few craters: Enceladus TITAN?? New moon: S/2004S2 8/16/04 Cassini 48 total (15 major) 3 - 5100 km (Titan) inside/outside rings icy (small amounts of rock) How large? Where? Composition? Activity?

24. Titan

25. Titan’s Atmosphere

26. Probe descent: January 14, 2005 Huygens Probe Descent Titan

27. ~10 km Huygens Probe on Titan Landing site

28. Titan’s Surface

29. Asteroids Ida Gaspra Mathilde

30. Asteroid Locations

31. NEAs This Week http://neo.jpl.nasa.gov/ca/ Size > 1 km = globally destructive

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

33. Asteroid Shapes & Sizes Mars

34. Asteroid Distances

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

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

37. Upcoming Mission: DAWN Ceres Vesta

38. Meteor-stuff

39. Peekskill, NY August 1992 Incoming Debris

40. Definitions

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

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

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

44. 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?

45. Bill Cassidy Where are meteorites found?

46. Meteor Crater Northern Arizona

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

48. 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

49. Comets May 7, 2004

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

51. nucleus Nucleus: Comet Head nucleus surface coma

52. Comet Tails

53. Comet Tails & the Sun

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

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

56. Comet Shoemaker-Levy 9