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Planetary Systems

Jovian Planets - Jupiter, Saturn, Uranus, Neptune

Outer Planets Gushing Moons As shown in Figure 07-11a, the giant outer planets consist mostly of hydrogen and helium gas and liquid, which surrounds a core of iron and rock and possibly a smaller amount of methane, carbondioxide and water ices. Jupiter is the largest planet, closely followed by Saturn. Uranus and Neptune are in comparison much smaller, although still significantly larger than any of the terrestrial planets. Jupiter is a "failed star" - it would have become a star igniting nuclear fusion at its core if its mass is about 80 times higher (the lowest mass limit for a star to form is about 0.05 MSun).

Figure 07-11a The Jovian Planets
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Figure 07-11b Gushing Moons [view large image]

Two of the Jovian Planets each owns a moon gushing out water from ocean under the icy surface. They are candidates for future missions to find life in alien seas (Figure 07-11b).