1. Comets May 7, 2004 Icy bodies left over from formation of Solar System Possibly brought water & organic material to early Earth

2. Anatomy of a Comet dust & frozen gas Head Tail Gas Tail Comet West Tail - two: dust + gas Head - nucleus + coma elliptical orbit

4. nucleus Nucleus: Comet Head nucleus surface Coma: coma irregular, < 10 km lump of porous rock & ice cloud of gas & dust around nucleus grows w/approach of Sun

9. Nucleus: Comet Wild 2 Jan. 2004 Stardust Sample Return Mission Jan. 2006: Return to Earth

10. Comet Tails Comet Hale Bopp Sun's heat vaporizes coma carried by solar wind ionized gas (electrically charged particles) dust released

11. Need sunlight: tail only appears when comet near Sun Sunlight = Tails

12. Where does gas tail point? Solar wind blows tail away from Sun

13. Where do comets originate? Kuiper Belt: - beyond Jovian planets (30 AU - 100 AU) - short-period comets Sedna Halley’s Comet

16. Where do comets originate? Oort Cloud: - immense spherical cloud - FAR outside solar system (10,000 AU - 100,000 AU) - long period comets Comet Hyakatuke Comet Hale Bopp

19. Comet Shoemaker-Levy 9 Impact: July 1994

20. Comet Shoemaker-Levy 9