• NAME
    Supreme God (Greek: Zeus)

    Jupiter is the largest planet and the first of the outer 'Gas
    Giants'. It consists almost entirely of Hydrogen and Helium
    like our sun. It would need to be at least 80 times more
    massive for it to begin thermonuclear 'burning' like our Sun.
    The pressure from the higher gravity starts the reaction. It is
    not certain if it has a solid surface or where it would begin.
    Heavier elements sink to the core so there must be a 'surface'
    at some point.

    The most famous Jovian feature is it's 'Great Red Spot'.
    It's a storm much like a terrestrial hurricane. The Red
    Spot has persisted since early telescopic observations (1660's).
    We don't know how long it existed in prior centuries.

    In 1994 comet Shoemaker-Levy 9 crashed piece by piece into
    giant Jupiter leaving huge black marks. Recently some old
    drawings of Jupiter have been found showing similar marks.
    Could other comets have crashed into jupiter? It seems likely.
    Jupiter's powerful gravity disrupts the orbits of incoming


    Sixty-three as of 7/23/06. The four largest are big enough to be worlds
    themselves. They are called the Galilean Moons because
    Galileo discovered them in 1610 when he turned the newly
    invented telescope to the heavens. There is also a faint ring
    discovered by the voyager spacecraft.

    Io - a world being constantly turned inside out. Jupiter's
    gravity is always pushing and pulling on it causing great
    internal heat. The heat is released in constant volcanic

    Europa - a moon with quite possibly a liquid ocean. It's
    surface is a very thick ice. Like Io it's flexing by Jupiter's
    gravity causing enough internal heat to melt the ice
    underneath the surface forming an ocean. Being further
    out than Io, it doesn't generate as much heat so there are no

    Ganymede - is the largest moon in the solar system with a
    varied surface of light and dark patches, craters and
    grooves. The grooves are likely caused by some sort of
    tectonic activity. It is actually larger than the planets
    Mercury and Pluto.

    Callisto - is the most cratered body in the solar system.
    This suggests that it is dead geologically and it's surface
    must undergo few changes over geologic time scales.

    Jupiter is brighter than all the stars in the sky. It tends
    to look sort of yellowish to me. An interesting challenge
    is to try and spot one of it's moons. When the planet is
    high in the sky, block it's light with a chimney or other
    such object and see if you can spot a very faint glimmer
    of light in close proximity to the planet. It is a very
    difficult observation. Use binoculars to give you an
    idea of what to look for.

    Jupiter may possess the most observable detail in a small
    telescope. Even the very smallest will show the four
    Galilean moons and two bands of reddish light crossing
    the planet's disk. The moons can be followed from night
    to night. Sometimes the moons can be seen crossing the
    disk (transit) or passing behind the planet (occultation).
    In a moderately sized scope one can see many bands of
    light that make up the planet's atmospheric currents.
    Much detail can be seen in the bands. The Great Red Spot
    can be seen as well.

A computer simulation. It depicts Jupiter as seen from it's moon Europa. It shows Jupiter's Great Red Spot. The moon passing across Jupiter is Io the innermost large moon. This is similar to what can be seen in a large amateur telescope. Io however, can not be seen in such detail. the view is from Europa, not earth, distorting Io's apparent size. Jupiter's faint ring is also seen crossing the disk. There are also some background stars.

Callisto - to the right is Valhalla basin, a large impact crater.
The bright patches are craters. 'Meteor hits' expose fresh ice
under the darker surface material creating bright patches.

Europa - showing cracks in it's icy smooth surface. Recent Galileo spacecraft images suggest an ocean beneath the ice.

Ganymede - largest moon in the solar system.

Io - volcano tortured world. One volcano can be seen erupting on the horizon.