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Comets

Comets. Small dusty/icy chunk of material few kms size (often characterized as “dirty snowball”) Originally condensed out of Solar nebula and still orbit Sun - primitive material Orbits often elliptical, large aphelion Partially vaporized when close to Sun - material

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Comets

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  1. Comets • Small dusty/icy chunk of material few kms size (often characterized as “dirty snowball”) • Originally condensed out of Solar nebula and still orbit Sun - primitive material • Orbits often elliptical, large aphelion • Partially vaporized when close to Sun - material (gases) then pushed by sunlight makes long tail • Gas tail always points away from Sun • Also dust tail along orbit

  2. COMET IKEYA-SEKI

  3. COMET WEST

  4. COMET HALE-BOPP

  5. Pushed by Sun Dust along comet’s orbit PARTS of a COMET

  6. Dust trail Dust trail Ion trail Ion trail Comet Hale-bop COMET TAIL ORIENTATION

  7. About the mass of Mt. Baker RECIPE for a COMET • Ingredients • Frozen methane • Frozen water • Frozen ammonia • Dust grains (dirt) • Traces of organic compounds and other chemicals • Directions • Mix into a ball about 10 km across containing 100,000,000,000,000, (1014) kg of this mixture

  8. COMET HALLEY

  9. COMET HALLEY’S ORBIT

  10. 1986 COMET HALLEY’S PATH 1910 and 1986 1910

  11. BAYEUX TAPESTRY

  12. Giotto-Adoration of the Magi

  13. ORIGIN of LONG PERIOD COMETS • Originate in Oort Cloud • a huge reservoir • ancient Solar System • material far from Sun • likely produced by • planetesimals ejected • by Jupiter and Saturn • Early on from inner • Solar System. • Passing star perturbes • Cloud sends lumps • inward - see as comets • when near Sun.

  14. KUIPER BELTPlanetesimals ejected from inner Solar System by stronggravitational fields of Giant Planets - some interact Jupiter and Saturn flung far out to Oort Cloud, interactions Uranus and Neptune pushed them out to Kuiper Belt Kuiper Belt

  15. KUIPER BELT OBJECT

  16. KUIPER BELT OBJECTS Pluto + 3 Moons Sedna e =0.86 Perihelion 76 AU Aphelion 975 AU! P =12,000 years

  17. METEORS AND METEORITES Meteors are parts of comets that pass through Earth’s orbit - burn up in Earth’s atmosphere Meteorites are ground up pieces of asteroids - off orbit - enter Earth’s atmosphere and survive passage

  18. Meteor Shower Comet breakup near perihelion Material spread out along orbit If Earth passes through comet debris - shower

  19. A METEOR STORM Leonid Shower 1833 Wood Cut

  20. LEONID METEOR SHOWERLong Exposure

  21. Dates Some Meteor Showers

  22. ANTARCTIC METEORITE Easiest to find meteorites against snow. Most found in Arctic or Antarctic Primitive material - planetesimals - useful for dating Solar System Many varieties - stony, metallic, often contain organic material

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