NEPTUNE   Eighth planet from the Sun

          Mean distance from Sun:    30.06 AU = 4,497,000,000 KM

          Diameter:                  49,500 KM

          Mass:                      17.23 Earths

          Density:                   1.7 grams / cubic centimeter

          Surface temperature:       < -250 F

          Orbital period:            164.79 years
        
          Similar in size and composition to Uranus, the eighth 
          planet is so far from Earth that ground-based observations
          reveal little detail.  Voyager 2 data confirm the presence
          of a tenuous ring system.  Neptune's largest moon, Triton,
          may be glimpsed in telescopes of apertures of 30 cm.
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