The littlest planet of all

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The littlest planet of all
Pluto is the most distant and smallest planet in
the solar system. It takes 6 days 9 hours to
rotate and 248 Earth years to orbit the Sun.
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Double Planet
Not only is Pluto the smallest planet but it is
smaller than seven of the solar systems moons.
Plutos only moon, Charon, is roughly half the
size of the planet. Some astronomers consider
Pluto and Charon to be twin planets, instead of
planet and moon.
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Unusual orbit
Pluto's orbit is highly eccentric. At times it is
closer to the Sun than Neptune (as it was from
January 1979 thru February 11 1999). Pluto is
locked in a 32 resonance with Neptune Its
orbital inclination is also much higher than the
other planets'. Thus though it appears that
Pluto's orbit crosses Neptune's, it really
doesn't and they will never collide.
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Frozen Planet
Pluto's exact composition is unknown, but its
density (about 2 gm/cm3) indicates that it is
probably a mixture of 70 rock and 30 water ice
much like Triton and other comets. This is a
true color image of Pluto. Its brown color is
thought to be frozen methane deposits.
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Hubble View
These pictures by the Hubble Space Telescope show
the surface detail on the two opposite
hemispheres of Pluto. Pluto has a thin
atmosphere that appears when it is close to the
sun. Its temperature ranges from -378 to -396
degrees F (-228 to -238 C).
Image NASA
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Kuiper Belt Objects

• Some believe Pluto to be a very large ice dwarf
  or Kuiper Belt Object.
• These objects are the size of asteroids or small
  planets, but are mostly ice, like a comet.
• They are very numerous and reside past the orbit
  of Neptune in the far outer solar system.

Image NASA
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More information

• - Pluto Diameter 2390 km, 0.2
• Earth Diameters Planetary Mass 1.25x1022 kg,
  0.0025 Earth
• masses
• Average Distance from Sun 5.913 billion km,
  39.53 AU
• (astronomical units)
• - Length of Day about 6.4 Earth Days
• - Length of Year 248.53 Earth Years
• - Day/Night Surface Temperature 54-59 degrees
  Kelvin
• - Number of natural satellites 1 Charon
• - Planetary ring system None
• - Average temperature 50 K (-223 C)
• - Atmospheric composition Methane (CH4),
  Nitrogen (N2)

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Earth Comparison
PLUTO
EARTH
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God of the Underworld
Pluto being a cold, dark planet was named after
the Roman god of the underworld where souls went
after death. It is also intended to evoke the
initials of the astronomer Percival Lowell who
predicted that a planet would be found beyond
Neptune
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You are Here
Image NASA
Pluto was discovered by the astronomer Clyde
Tombaugh at the Lowell Observatory in Arizona on
February 18, 1930. Its moon, Charon, was
discovered in 1978 by Jim Christy.
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New Horizons- NASA
Image NASA
NASAs New Horizons is the first mission to the
last planet - the initial reconnaissance of
Pluto-Charon and the Kuiper Belt - sent out to
explore the mysterious worlds at the edge of our
solar system. New Horizons is scheduled to launch
in January 2006.