Planets

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					Planets
What do you know about
     the planets?
Planet order plus the asteroid
      and Kuiper Belts
Terrestrial versus jovian planets
   Terrestrial: rocky
    with small amounts
    of ice
   Earth: only planet
    with liquid water
   Jovian: large
    amount of
    ammonia and
    methane ice with a
    rocky or metallic
    core
 Relative
planet size
    Mercury
   Smallest
   Densest
   Craters and lava flows visible
   Cooled, lacks tectonic activity
   Thin layer of gases
   Magnetic field
   Perhaps ice at poles
   Extreme temperatures:
    • Sunny side 950 degrees F
    • Dark side: -346 degrees F
 Why are craters rare on Earth and
common on the Moon and Mercury?


  The Earth’s surface is
     mobile due to
    processes that
     produce plate
       tectonics.
     Messenger spacecraft


   Launched 2004
   Orbit Mercury,
    March 18, 2011
    Messenger: mission
    to Mercury
   Why so dense?
   Core size and
    composition?
   Magnetic field?
   Ice? If so
    composition?
   Extreme
    temperatures-results?
   Only 45% of surface
    has been observed
Gravitational Force: the attraction
between two masses (remember
      Newton’s equation?)
   Your weight is the attraction between
    the Earth’s mass and yours
   What would be your weight on
    Mercury?
    • More or less?
           Gavitational pull
   Earth: 150 pounds
   Mercury: 57 pounds
       Venus
   Slightly smaller than Earth
   Very hot: 900 degrees F
   Retrograde rotation (opposite the
    Earth)
   Visible in the sky: the morning “star”
      Venus’ Atmosphere
   Water and carbon dioxide:97%
   No liquid water
   Extreme pressure: 92 X pressure on
    Earth at sea level (same as .6 miles
    deep in ocean)
   Electrical storms within the clouds
   Sulfuric acid clouds
    • Can move at 350 KM/hr
Greenhouse effect: explanation
to why Venus’ surface is so hot
   97%CO2 ,3% N



                           Water vapor
                           and Carbon
                           dioxide
                           absorb
                           infrared
                           radiation
                   Venus
   Tectonic activity
   Mantle convection
   Upwelling of
    mantle material
   Down-welling of
    mantle material
   Basaltic volcanism
                           Radar data enabled
   Lack of crater         scientists to penetrate
    impacts implying       Venus' thick clouds and
    mobile surface         create simulated views
                           of the surface.
      Exploring Venus

   Magellan, 1990-
    1995
   Radar images of
    Venus’ surface
      Mars

   4th planet, red planet
   Temperature: -207 degrees to 32
    degrees F
   Atmosphere: 95 % carbon dioxide
   Water once flowed on surface
   Sea existed perhaps 5 million years
    ago
             Olympus Mons




   Explored remotely by man
   Thought most likely to have had life
   Evidence of water erosion: Valles
    Marineris
    Volcanism: largest mountain in the
    solar system (24x500 KM)
   Polar ice caps of solid water and
    Carbon dioxide
         Comparison to Earth
   When a rocky planet’s core cools
    • Magnetic field is lost
    • Tectonic activity ceases
    • Atmosphere is lost
               Mars’ Moons




Deimos: 7.5
                                  Phobos
miles across



                  Asteroid like
       Sunrise on Mars, August 26, 2008
Mars




       The Phoenix Lander arrived May 25.
       2008
       •Polar region: explore the possibility of
       life; characterize climate; the geology
       •May , 2010 transmitting data ceased
Picture taken on December 21,
2008 by Mars reconnaissance
  orbiter ( in orbit since 2001)
      Jupiter

   1000 Earths could fit inside an empty
    Jupiter
   Atmosphere: H, He some methane,
    ammonia
   Surface pressures so great H gas
    converted to liquid
   Metallic hydrogen core
   63 Moons
   Orbit around Sun: 12 Earth years
   Rotation: 9 hours, 56 minutes
                 Jupiter
   Pressure breaks up atoms: electrons
    flow freely, single protons causes
    Hydrogen to become metallic
   Magnetic field: 10 x stronger
    than Earth
    Great Red Spot
   1st photographed by
    Voyager 1, 1979
   Colors are due to
    warm air rising and
    cooler air sinking
   Winds blow counter
    clockwise around the
    spot
   Two times larger than
    Earth
   Migrates east and
    west
       Galileo spacecraft: launched
            1989 crashed 2003
   1st to fly past an asteroid
   Measured Jupiter’s
    atmosphere
   Evidence of salt water on
    Europa, Ganymede, and
    Callisto
   Volcanism on Io
   Purposefully crashed into
    Jupiter to discover           Arrived to Jupiter, 1995
    temperatures and
    pressures
 Galileo: observed 4 of Jupiter’s 63
               moons




                                     Ganymede
               •Europa
Io
                                                Callisto

6 year mission by the spacecraft Galileo
                   Io




•The most volcanically active in solar system
•Some volcanoes are hotter than on Earth
•100 foot tidal pull on surface
            Europa




•Roughly the size of our moon
•More water than Earth
•Thin oxygen atmosphere
•May have a liquid ocean below icy surface
•Cooled, icy crust, brown = non-ice
•Internal source of heat
        Ganymede




•Largest moon
•Has a magnetic field
•Rocky core
•Icy outer layer
                    Callisto

•Size of Mercury
•Cratered surface
•Rocky core
•Icy mantle
         Saturn


   6th planet
   Atmosphere:75% Hydrogen, 25% Helium
   Rocky, metallic interior core; liquid
    metallic hydrogen
   Rings are composed of debris held in orbit
    by Saturn’s gravitational force
   Some debris is thought to come from
    volcanism on Saturn’s moon IO
                   Saturn
   Hubble photograph
   1996-2000
   Rotates on its axis
   Orbiting around
    the Sun
   Each season is 7
    years
   30 Earth years to
    orbit the Sun
   10.5 hour rotation
                Saturn’s Rings
   Water ice, dust, and
    gases
   Particles range in size
    from pebble to house
    size
   18,000 miles wide
   .6 mile thick
Saturn has 62 Moons
     Spacecraft Cassini (artist’s
          interpretation)
Since 2004, this spacecraft is collecting data from
Saturn and several moons




                                           Picture of
                                           one moon
                     Titan

   Largest satellite of
    Saturn
   Rocky core, shell of
    water ice
   Atmosphere:
    nitrogen and
    methane
                        Uranus
   Blue-green color: crystals
    of methane
   Atmosphere: H and He
   Interiors are composed of
    methane, ammonia and
    water
   Core is composed of rock
    and metal
   84 Earth year orbit
   17 hour rotation
   98 degree tilt on its axis
             Voyager 2, 1986
   Magnetic field on
    Uranus is tilted at
    58 degrees
   Uranus has a
    number of rings
   Ranging from3-60
    miles thick
                   Neptune
   Magnetic field is
    tilted at 50 degree
   4 X bigger than
    Earth
   Orbit: 165 Earth
    years
   H, He, water and
    silicates
   Solid rocky core
   11 satellites
                          Asteroid Gaspra
        Asteroids
   Small fragments of
    rock from the solar
    system’s formation
                                        19x12x11 kms




                                    Red indicates
                                    asteroid belt
                                    path
       Asteroids passing Earth
   Two asteroids pass
    Earth at about the
    distance of the
    Moon
   One is 32-65 feet
    in size
   The other is 20-46
    feet in size
          Dinosaur Extinction
   65 million years
    ago
   Asteroid impact
   190 miles in
    diameter
   Sent debris into
    the atmosphere,
    blocking solar
    radiation
   Reduced plant
    growth
       Comets



   Composed of ice (ammonia, methane,
    carbon dioxide, and carbon monoxide)
   Rocky core
   Tail: solar wind and radiation pressure
    move ionized gases and dust
   Sublimation: the change in state from
    solid to gas without passing through the
    liquid stage
                Kuiper Belt
   Comets orbit the
    Sun in the same
    plane as the
    planets
                Meteoroids
   Less than a meter
   Debris from
    asteroid belt,
    interplanetary
    material or the
    moon
   Friction from the
    meteoroids and air
    heats both and we
    see a “shooting
    star”                Next meteor showers:
                         August 12-13, 60
                         meteors/hour
            New Information
   Kepler-11 star,
    2000 light years
    away
   Appears to have
    rocky planets
   Most complete
    planetary system
This concludes the astronomy
     portion of the class.

				
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posted:3/14/2012
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