Comets Asteroids Meteors and the things

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					Comets, Asteroids, Meteors
         OH MY!
             Bause
  North Farmington High School
      What’s the difference?
• Comets- small body of ice and dust in a
  highly elliptical orbit around the Sun.
• Asteroids- Large rocky body (≥ few
  hundred meters in diameter) that orbits
  the Sun.
• Meteoroids- small rocky body (< few
  hundred meters) in orbit around the Sun.
Comet Hale-Bopp 1997
Comet Diagram
•   Dust tail is opposite the motion of the comet. Trail of debris left behind.
•   Ion tail is ALWAYS on the opposite side of the Sun. Solar wind
    (charged particles, electron and protons, shot outward from the Sun).
    The charged particles excite the gases emitted from comet and give off
    light (usually blue).
•   Both tails get bigger/brighter the closer to the sun.
     – Dust tail because the sun warms the comet, sublimating the gases and
       allowing more debris to fall off.
     – Ion tail because more charged particles from the sun are colliding with
       increasing gases given off from the comet.
Orbit
                       •The orbit of comets are highly
                       eccentric (elliptical)
                       •UNLIKE asteroids and planets,
                       the orbit is not necessarily on the
                       same plane as the path planets
                       take around the Sun.
                       •Long Period comets orbit Sun
                       over 100 yrs
                           - Hale Bopp 2600 yrs.
                       •Short Period less than 100
                           - Haley's comet 76 yr. (2062)
                           - Comet Encke shortest
                           orbital period 3.3 yrs.


  Comet Hyatuke 1996
                Composition
• Dirty Snowballs
  – Mostly rock and ice surrounded by solid H2, water,
    CH4, CO, O2, which sublimate (solid to gas) when
    approach the sun.
  – Recently found CaCO3!!!
• Missions:
  – Deep impact. Study the nucleus of Comet Temple 1.
    Detonation was July 4th, 2005.
  – Stardust. Followed comet Wilde 2 and collected
    comet dust. Returned to Earth Jan. 15, 2006
• Dust Tails leave a trail of debris. If the Earth
  passes through debris we get a meteor shower.
• Surface of Comet
  Temple 1
  – Taken from the
    Deep Impact
    Mission
                Meteors
             “Shooting stars”
• Dust-like comet fragments that enter our
  atmosphere at high speeds. 10 to 50 mps
  (up 180,000 mph)!
• They leave a brief flash called a train in
  the upper atmosphere. caused by gases
 becoming charged in our atmosphere
• Usually the size of sand or less.
• Fireball- long lasting shooting star (few
  seconds). Usually basketball size or more.
Fireball during Leonids
       (Mid-November)
Another, cooler looking, Fireball
                Meteorites
• Meteors that make it to the ground.
• kinds
  – Stoney- mostly rock (feldspar) (called
    chondrites)
  – Iron- metal mix
• Largest ever found
  – Hoba meteorite. Over 50 tons.
Largest Ever
                 •Most meteorites
                 slow to terminal
                 velocity due to air
                 friction. 150 to 200
                 mph (depending on
                 mass)
                 •If they are traveling
                 at greater speeds, it
                 will result in craters
                 on the Earth’s
                 surface.
                 •*** This guy made the mistake of calling
                 NASA. They took the meteorite worth quite
                 a bit of money. SO, he sold his car on
                 ebay. Got 100 grand.
APOD Nov. 2002
The Meteor Crater




99% + of projectile is vaporized   100 meter projectile created 1 mile
if they are over 50 tons.          diameter crater.
If less, they slow to term. vel.   20:1 ratio
                                   50,000 yrs old
 Chicxulub Crater
Yucatan Pennisula
              • 120 Mile wide
                crater formed
                from a 6 mile
                wide asteroid.
              • Marks the end of
                the Mesozoic-
                Killed 70% of
                ALL species
                (including dinos)
              • Mostly buried
                today.
              Meteor Showers
• Increased count per hour.
  – On a normal day you should see 1/hour.
  – During a shower, up to 100/hour
• When Earth travels through dust trail left behind
  by comet (from dust tail). OR ejecta from meteor
  collision on another planet.
• Name after constellation they appear from.
  –   Perseids- Aug 10-13
  –   Leonids- Nov. 16-17
  –   Geminids- Dec. 10-15
  –   Many more
Leonids 1998
                Asteroids
• “Minor Planets”
• Found in 2 belts.
  – The Asteroid Belt (1/2-way btwn Mars & Jup)
  – Kuiper Belt: Beyond Neptune… includes
    Pluto, Xena & Sedna. A few bil miles to 10’s
    of billions of miles.
• Mostly orbit on same plane as planets, but
  finding more and more that don’t.
              Oort Cloud
• Beyond Kuiper belt. Home to trillions of
  icy/rock objects up 5 trillion miles away
  (almost a lightyear).
• Cannot see these objects yet, but it is
  believed there could be objects as big as
  the Earth.
• We see 10 or so comets a year originating
  from the Oort cloud.

				
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posted:11/30/2011
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