Fluid Spheres on Other Planets and Moons

الأحد مايو 17, 2015 5:12 pm

Fluid Spheres on Other Planets and Moons

Earth is not the only planetary body in the solar system with fluid

spheres. Venus and Mars both have atmospheres. Like Earth, the mass

of each of these planets is large. The mass of each is large enough to

create a gravitational field. This keeps its atmosphere from escaping into

space. Judging from their atmospheric pressures, the mass of Earth’s

atmosphere is about 100 times greater than Mars. It is 100 times less

than that of Venus. There are traces of an atmosphere on Mercury and

the Moon. Early in their formation, they may have had atmospheres.

However, because of their weak gravitational fields their atmospheres

were probably lost into space. One of Jupiter’s moons, Io, has an

atmosphere that is strongly affected by the Jupiter’s gravitational field.

Europa, another of Jupiter’s moons, has a thin oxygen-rich atmosphere.

Titan, Saturn’s largest moon, is icy and rocky. It has an atmosphere rich in

nitrogen with clouds of methane. Its fluid spheres contain rare features.

These include ice volcanoes and liquid hydrocarbon lakes.

Earth’s fluid spheres are unique among the other planets. Earth is the

only planet with abundant free oxygen. Venus and Mars also have

oxygen, but it is tied up in carbon dioxide molecules. Earth also has

abundant water in all three states. Venus has a very small amount of

water. Mars shows evidence of ancient stream erosion but no longer has

liquid water on its surface. Mars does have ice at its poles. Because of the

different composition of their atmospheres and their distances from the

Sun, the surface temperatures of each of these planets varies greatly from

480°C for Venus to 15°C for Earth.

الأربعاء مايو 20, 2015 9:49 pm

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رد: Fluid Spheres on Other Planets and Moons