Page 50 - Curriculum Visions Dynamic Book

Solar System, most of it as gas and most of that in Jupiter. Satellites of the planets, comets, asteroids, meteoroids, and interplanetary medium comprise the remaining 0.015%.
Gas giants
The largest planets are all rotating balls of gas with little or no discernable rocky core. They also have very
low densities. (Saturn’s density is so low that it
would float on water.) They are somewhat similar in composition to the Sun. They also have numerous moons and rings made of small particles of rock
that were never captured and incorporated in the planets. Their atmospheres are mainly hydrogen and helium.
Rocky planets
By contrast, the smaller planets are nearly all made of rock, with only a small mass of gas forming a thin shell. These planets, apart from Pluto, which seems to be a
mixture of rock and ice, have much higher densities than the gas giants. None has rings, and few have moons. Although all the large bodies in the Solar System
(including the Sun) have an atmosphere, it is most apparent around the rocky planets because most of the mass of these planets is solid material. The line between the atmosphere and the planet’s surface is thus extremely clear- cut, unlike the situation on the gas giants and the Sun.
Although the gases surrounding each rocky planet vary in proportion, they are usually based on oxygen.
Moons
Although we can separate the planets into broad groups, there is great variation among the moons that orbit them. For example, Jupiter’s moons are completely different from one another, with the innermost—Io—being one of the most active volcanic places in the Solar System, while its neighbor, Europa, is completely devoid of such activity
For more on Jupiter’s moons see Volume 5: Gas giants.
Mercury
Venus Moon
Mars
Earth
Saturn
Jupiter
Uranus
Neptune
Pluto
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