2. Bit of Administration …. Washburn ObservatoryWashburn Observatory –Thursday, 8:30 - 9:30 PortfoliosPortfolios –Due Thursday, April 29, because of possible TAA strike Put in box outside 6522 SterlingPut in box outside 6522 Sterling –All 5 must be securely bound together, including ones already graded –Late portfolios will lose credit Lab 3Lab 3 –Due Thursday, April 29, because of possible TAA strike Put in box outside 6522 SterlingPut in box outside 6522 Sterling –Problem 5, HW 1 is a good starting point for the lab questions –Note typo in Question 3 - “Jupiter” => “Saturn”

3. THE EXTRA-SOLAR PLANET PROJECT Phase 1: Last week’s quiz. Phase 2 : A Web-Lecture on Extra-Solar Planets. –Learn about extra-solar planets and have opportunity to earn 5 pts extra credit. 2 pts for evaluation questions 3 pts for success on quiz –Preparation for next week’s discussion sections (5/3-5/7). –Access: http://eteach.engr.wisc.edu/meibom/espp/index.html –Speed: 300 Kbps, 100 Kbps, and 37 Kbps. The hardware requirements for viewing the lecture are: –A computer with connection to the Internet. –Computer speakers or headphones. The software requirements for viewing the lecture are: –Windows Operating System. –Internet Explorer version 5.5 or later. –Power Point 2002 or later ("Power Point Animation plug-in"). Campus computer-labs: –http://www.doit.wisc.edu/computerlabs/index.asp –Bring headphones!

4. Asteroids, Comets, Meteors, and Pluto

6. Asteroids Asteroids

7. Asteroids, Comets, Meteors, and Pluto Asteroids Asteroids

8. Asteroids, Comets, Meteors, and Pluto Asteroids Asteroids 150,000 catalogued 150,000 catalogued as many as “grains of sand on the beach” as many as “grains of sand on the beach” Size - few km typical, 1000 km largest (half Pluto) Size - few km typical, 1000 km largest (half Pluto)

9. Asteroids, Comets, Meteors, and Pluto Density - 2 - 3 gm/cm 3 Density - 2 - 3 gm/cm 3 Note: About as expected for rock in low gravity Note: About as expected for rock in low gravity Shape - Irregular because of low mass => low gravity Shape - Irregular because of low mass => low gravity Asteroids Asteroids 150,000 catalogued, as many as grains of sand on the beach 150,000 catalogued, as many as grains of sand on the beach Size - few km typical, 1000 km largest (half Pluto) Size - few km typical, 1000 km largest (half Pluto)

10. Asteroids, Comets, Meteors, and Pluto Asteroids Asteroids Orbits Orbits

11. Asteroids, Comets, Meteors, and Pluto Asteroids Asteroids Orbits - Earth-Crossing Asteroids Orbits - Earth-Crossing Asteroids

12. Asteroids, Comets, Meteors, and Pluto Comets Comets

13. Asteroids, Comets, Meteors, and Pluto Ices and Rock Icy Planetesimal 10 km “Nucleus” Comets Comets Plasma (Gas) Tail Dust Tail Tail Coma

14. Asteroids, Comets, Meteors, and Pluto Comets Comets Orbital Properties Orbital Properties Long period comets Long period comets P ≈ 10 5 - 10 6 yr => A ≈ 10,000 AU P ≈ 10 5 - 10 6 yr => A ≈ 10,000 AU Elliptical to hyperbolic orbits Elliptical to hyperbolic orbits Come from all directions - “isotropic” Come from all directions - “isotropic”

15. Asteroids, Comets, Meteors, and Pluto Comets - Oort Cloud Comets - Oort Cloud Perturbations by passing stars cause comets to fall in Perturbations by passing stars cause comets to fall in Origin of long-period comets Origin of long-period comets 1 trillion comets

16. Asteroids, Comets, Meteors, and Pluto Comets Comets Orbital Properties Orbital Properties Long period comets Long period comets P ≈ 10 5 - 10 6 yr => A ≈ 10,000 AU P ≈ 10 5 - 10 6 yr => A ≈ 10,000 AU Elliptical to hyperbolic orbits Elliptical to hyperbolic orbits Come from all directions - “isotropic” Come from all directions - “isotropic” Short period comets Short period comets P A A < 50 AU Highly elliptical Highly elliptical In ecliptic plane In ecliptic plane

17. Asteroids, Comets, Meteors, and Pluto Kuiper Belt ObjectsKuiper Belt Objects

18. Asteroids, Comets, Meteors, and Pluto Kuiper Belt ObjectsKuiper Belt Objects

19. Asteroids, Comets, Meteors, and Pluto Kuiper Belt ObjectsKuiper Belt Objects Sedna Pluto and Charon Triton 650 KBOs discovered 100,000 with radii > 10 km

20. Asteroids, Comets, Meteors, and Pluto Comets - Evolutionary PictureComets - Evolutionary Picture

21. Primordial Icy Planetesimals Fragmented Icy Planetesimals (KBOs) Rocky Planetesimals Icy Planetesimals Jupiter Forms Oort Cloud Kuiper Belt

22. Asteroids, Comets, Meteors, and Pluto Comets Comets Periodic Comets - e.g., Halley’s Comet Periodic Comets - e.g., Halley’s Comet Highly elliptical Highly elliptical P < 200 yr P < 200 yr Put into short periods by Jupiter Put into short periods by Jupiter

23. Asteroids, Comets, Meteors, and Pluto Comets Comets Periodic Comets - e.g., Halley’s Comet Periodic Comets - e.g., Halley’s Comet Highly elliptical Highly elliptical P < 200 yr P < 200 yr Put into short periods by Jupiter Put into short periods by Jupiter Fragmented after many passages around Sun Fragmented after many passages around Sun

24. Asteroids, Comets, Meteors, and Pluto Meteors Meteors Showers - debris of old comets Showers - debris of old comets Earth orbit Past Comet

25. Asteroids, Comets, Meteors, and Pluto Meteors Meteors Types - Processed Meteorites Types - Processed Meteorites Stony Meteorites Stony Meteorites 93% 93% Just like crust of Earth Just like crust of Earth Iron Meteorites Iron Meteorites 6 % 6 % Crystallization patterns => long cooling times Crystallization patterns => long cooling times

26. Asteroids, Comets, Meteors, and Pluto Meteors Meteors Types - Primitive Meteorites Types - Primitive Meteorites Stony, with trace of pure metallic flakes Stony, with trace of pure metallic flakes Carbonaceous chondrites Carbonaceous chondrites Carbon compounds, and even water Carbon compounds, and even water

27. Asteroids, Comets, Meteors, and Pluto Summary Summary Asteroids Asteroids Rocky Planetesimals Rocky Planetesimals Comets Comets Long - Period = Icy Planetesimals Long - Period = Icy Planetesimals Short - Period = Fragmented KBOs Short - Period = Fragmented KBOs Pluto, Sedna, Triton, Kuiper Belt Objects Pluto, Sedna, Triton, Kuiper Belt Objects Icy Planetesimals Icy Planetesimals Meteors Meteors Primitive Meteors = Rocky Planetesimals Primitive Meteors = Rocky Planetesimals Processed Iron and Stony Meteorites Processed Iron and Stony Meteorites Fragmented asteroids Fragmented asteroids Meteor Showers Meteor Showers Fragmented comets Fragmented comets

28. Asteroids, Comets, Meteors, and Pluto