Montage of Jupiter and its Four Largest Moons Here is a montage that shows Jupiter's Great Red Spot, along with its four largest moons. From top to bottom, they are Io, Europa, Ganymede and Callisto. These pictures were taken using the Galileo spacecraft that was launched in 1989. As you scroll down, you will see photographs of the Great Red Spot and more detailed pictures and discussion of the aforementioned moons.

Jupiter's Great Red Spot This true-color picture captures the subtle  shadings of Jupiter's Great Red Spot, a massive, long-lived storm system in the planet's thick atmosphere.

Volcanic Activity on Io Io is the most volcanically active world in our solar system. In fact, in this photo of Io, a blue volcanic plume can be seen at the very left side of the picture. To see another very nice picture of Io, click here.

If you click on the picture, you should be presented with a BBC article that describes some of the unusual activity to be found on Io. This will open a new browser window. When you are finished reading the article, just close the window.

Europa's Icy Surface May Conceal Ocean, Life This is a mosaic that provides an excellent view of the side of Europa that faces Jupiter. A liquid ocean may lie beneath Europa's icy surface. Owing to the possible presence of this water, some scientists theorize that there might be primitive life on Europa. If you click on the image, you will be able to read a BBC article that describes Europa in more detail. This will open a new browser window.

Ganymede's Polar Caps      In this picture of Ganymede, polar caps can be seen at the top and bottom. Some cratering can also be seen, but this view  has most of Ganymede in darkness. The regions that appear in violet are thought to correspond to frost particles.

Crater String on Ganymede This picture shows a series of craters on Ganymede; it is thought that these craters may have been caused by a comet that broke up into separate fragments just as it was about to hit the surface.

Cratered Callisto Callisto is considered to be the most cratered celestial body in our solar system. (Please note: This picture employs a false color overlay that presents an image that is not quite what one would see with the naked eye. Scientists use false colors in order to see features that otherwise would be difficult or impossible. )

Articles on Jupiter and its Moons New Galileo Images Reveal Hawaiian-Style Volcano On Io Jupiter's Moon Io: A Flashback To Earth's Volcanic Past Battery Acid Chemical Found On Jupiter's Moon Europa Chlorine Discovery Near Jupiter Moon Hints At Salt Presence Hubble Clicks Images Of Io Sweeping Across Jupiter Searching For Life On Jupiter's Moon Europa Liquid Ocean On Jupiter's Moon? ASU Geology Team Collects Europa Data Jupiter's Moon Callisto May Hide Salty Ocean Scientists Find Solar System's Hottest Surfaces On Jupiter's Moon Io Galileo Spacecraft Sees Dazzling Lava New Class Of Dust Ring Discovered Around Jupiter Galileo Finds Arizona-Sized Volcanic Deposit On Jupiter's Moon Io Jupiter's "White Ovals" Take Scientists By Storm Galileo Finds Jupiter's Rings Formed By Dust Blasted Off Small Moons Oxygen Discovered At Callisto's Surface, Sulfur Dioxide Sources at Io Jupiter's Atmosphere Gives Clues On How Solar System Started  Galileo Spots New Volcanoes on Io.