1. Comets, Meteors, and Asteroids

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

3. Comet Structure Nucleus Coma Tail 10 km “Dirty Snowball”
Cloud of evaporated ices and ions
may be 100,000 km in diameter
Tail
Always points away from Sun
Due to Solar Wind & Radiation Pressure

4. The Oort Cloud In 1950 Jan Oort noticed that
no comet has been observed with an orbit that indicates that it came from interstellar space,
there is a strong tendency for aphelia of long period comet orbits to lie at a distance of about 50,000 AU, and
there is no preferential direction from which comets come.

5. The Oort Cloud

6. Comet Halley

7. Bayeaux Tapestry Norman Invasion of 1066

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

9. Comet Nucleus

10. Comet of 1577

11. Comet Pons-Encke, 1804

12. Hyakutake

13. Hale-Bopp

14. Comet West

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

16. Why After Midnight is Best
Orbital Velocity
Rotational Velocity

17. Shower Radiant
The ‘leftovers’ of a comet. Apparent point of origin of a meteor shower.

18. Shower Radiant

19. The 1833 storm

20. The 1966 storm

21. 1997 Leonids from Orbit

22. Two Showers for Halley

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

24. Barringer’s Crater
An iron meteorite 100 feet across and 70,000 tons slamed into the Earth at about 43,000mph in the Arizona desert near Flagstaff 40,000 years ago. Barringer Crater is 4,100 feet wide and 571 feet deep.

25. Other Impact Craters

26. Tunguska, 1908

27. How Much Damage?

28. Asteroids
Apollo
Trojans

29. Ida - Dactyl

30. Gaspra

31. Kirkwood Gaps

32. Asteroids Elsewhere

34. Sedna