Some Facts:

• orbits Sun in
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• Core: the core may be liquid or "slush" rather than solid. The inner atmosphere is believed to be "liquid metallic hydrogen" - which could explain Jupiters extreme magnetic fields.
• Colors: the orange and brown colors may be due to organic compounds produced by the atmosphere's small amounts of carbon combining with hydrogen and small amounts of oxygen. Alternatively, the color may be from sulfur and phosphorus.
• Great Red Spot: spacecraft have shown this to be a whirling storm. It varies in color and size over time; presently it is not very red, and is about 14,000 miles by 7,000 miles.The color may be due to phosphorus. It drifts in longitude, but stays at about 22 deg. S. latitude.
• The four "Galilean" moons Io, Europa, Ganymede and Callisto are all planet-sized - they would be naked-eye objects except for the glare of Jupiter.
  Ganymede (larger than Mercury) and Callisto are both icy and cratered; Ganymede shows evidence of past tectonic activity; Callisto does not.
  Europa is virtually crater-less and has a smooth icy surface covered in shallow cracks.
  Io is actively volcanic, probably due to gravitational pulls of Jupiter and the other moons.
• Jupiter has many additional small moons, all too small for telescopes.
• Early space missions showed that Jupiter has a thin, dark ring.
  
• Comet Shoemaker-Levy 9 crashed into Jupiter in fragments July 16-22, 1994.
  

Observing Notes

• Jupiter is in Leo in 2004, visible in the evening sky through July.
• Jupiter is brighter than any star in the sky.
• We can usually see the banding of bright zones and dark belts on the surface. The bright zones are areas of hot gas rising to the cloud tops; the dark belts are areas of cooler gas pouring down toward the interior.
• Moons: we can usually see the beautiful "string-of-pearls" effect of the 4 "Galilean" moons.
  These are (inner to outer): Io, Europa, Gannymede, Callisto
• Jupiter's fast rotation flattens it a little - this may be visible.
• For transit time of Jupiter's Red Spot: skyandtelescope.com/observing/objects/planets/article_107_1.asp
  

Filters:
(from the information provided with Celestron filter packages)

The following filters all say: "Penetrates and darkens the atmospheric currents containing low-hue blue tones and enhances the orange and red features of belts and zones. Also useful for studies of the polar regions."

• Yellow (#8, 83% T)
• Deep Yellow (#12, 74% T)
• Deep Yellow (#15, 67% T)

Other filters:

• Orange (#21, 46% T): Improves structure of the Jovian belts and enhances festoons and the polar regions. [This one is supposed to be good for the Red Spot.]
• Red (#25, 14% T): Useful for studying the bluer clouds
• Blue (#38a, 17% T): Enhances the boundaries between the reddish belts and adjacent bright zones. Also uesful on the Great Red Spot.
• Light Green (#56, 53% T): Improves low-contrast hues of blue and red in the Jovian atmosphere
• Green (#58, 24% T): Increases the visibility of the Great Red Spot. Useful for observing the low-contrast hues of blue and red that exist in the Jovian atmosphere.
• Light Blue (#80a, 30% T): Enhances the boundaries between the reddish belts and adjacent bright zones. Also uesful on the Great Red Spot.
• Pale Blue (#82a, 73% T): Enhances the boundaries between the reddish belts and adjacent bright zones.

Exploratory missions: (information on NASA Jupiter programs: galileo.jpl.nasa.gov/jupiter/jupiter.html

• Pioneer 10 (1973)
  
• Pioneer 11 (1974)
  
• Voyagers 1 & 2 (1979)
  
• Ulysses (1992)
• Galileo (1995) - probe and orbiter