NEPTUNE


  • NAME
    God of the sea (Greek: Poseidon)

  • ABOUT NEPTUNE
    Neptune is the outer-most gas giant and the eighth planet.
    Like the other gas giants it is mostly Hydrogen and Helium.
    A small amount of methane in it's atmosphere absorbs
    the longer wavelengths leaving the planet with it's
    beautiful blue appearance. Neptune's atmosphere is much
    more active than Uranus'. It had a great dark spot much
    like Jupiter's Red Spot. It seems to have disappeared since
    the Voyager encounter 8 years ago. Neptune is more
    dynamic than bland Uranus, showing much more details in
    it's clouds. Neptune has an internal heat source that drives
    it. What the source of the heat is, is not clear. It radiates
    as much heat as Uranus but is twice as far from the sun.

  • DISCOVERY DATE
    1846. It was actually 'discovered' mathematically. Continuing
    observations of Uranus indicated something was wrong. It
    was not where it was predicted. The conclusion was that
    something was pulling Uranus off-course. Two
    mathematicians working independently deduced possible
    locations, for this hypothetical body causing Uranus'
    misbehavior. The two co-discoverers were John Couch Adams
    and Urbain Jean Joseph Le Verrier who both predicted
    Neptune's position with remarkable accuracy. It was within
    minutes that observers Johann Gottfried Galle and Heinrich
    d' Arrest found Neptune near the predicted location.
    Actually the planet was seen two hundred years earlier
    by Galileo. He drew it's position but with his small
    telescope, he did not recognize it as a planet.

  • MOONS
    Thirteen as of 7/23/06. Two were discovered pre-voyager, the other six by
    voyager II. It's largest moon Triton is peculiar in that it's
    orbit is retrograde. There is no definite explanation for why
    it orbits in an opposite direction from other solar system
    objects. Some theorized it is a captured moon and not part
    of neptune's formation. Triton may actually be quite like
    Pluto and it's moon Charon. It may have wandered too close
    to Neptune and was captured by it's gravity. Triton also
    had nitrogen geysers on it's surface. Some seemed to be
    erupting when Voyager passed by.

    Neptune possesses rings like the other Gas Giants. Before
    Voyager arrived they were detected on Earth by the
    same method as Uranus (occultation of a star). The rings
    seemed to be incomplete though, they seemed like 'ring arcs'.
    The mystery was solved by Voyager II. It seems the rings are
    complete but have certain areas of greater concentration
    of ring material. This is caused by moons whose gravity
    causes concentration of ring material in certain segments.

  • OBSERVING - NAKED EYE
    I am not aware of a naked eye observation. It may be possible
    from a mountaintop under extremely dark skies. If you don't
    have such an observing site, don't bother.

  • OBSERVING - TELESCOPE
    A small telescope will show it's small blue disk. Any more
    than that is extremely difficult. It may be possible to see
    spots and bands as this has occasionally been reported
    with larger amateur telescopes under good conditions.
    Another observation to try with a moderate sized scope
    is to spot the moon Triton. This is an easier observation
    than any detail on Neptune.


A view of Neptune from it's moon Triton. The great dark spot and rings are visible. The computer animation is 6 days, the orbital period of Triton. The disk of Neptune from Triton would appear about 16 times the diameter of our moon in the sky.


Neptune's clouds from Voyager including the 'Great Dark Spot'.


A closeup from Voyager of Neptune's moon Triton.


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