The Outer Planets: Jupiter, Saturn, Uranus, and Neptune

The Outer Planets: Jupiter, Saturn, Uranus, and Neptune — page 7
THE OUTER PLANETS JUPITER SATURN URANTS AND NEPTUNE Jupiter is huge it would have to be about 80 times more massive to generate nuclear reactions and become a star Hot glowing lava erupts from a volcano on Jupiter's moon lo in an image captured by the Galileo orbiter It is a mosaic of several images including enhanced color images taken in visible light The bright white yellow and orange at left are false colors added to images taken at infrared wave lengths to indicate temperature White is the hottest and orange the coolest NASA JPL California Institute of Technology Nevertheless Jupiter reigns at the center of a system of dozens of moons like a minia ture solar system Four of the moons are quite large and would probably be considered plan ets themselves if they did not orbit a planet They are remarkably dissimilar worlds Io is the most volcanically active body in the solar system Frequent eruptions renew its surface and cover over any craters that form Europa s surface is also fairly young but its features are smoothed not by fiery lava but by water ice 12