Special TopicsMartian Soil
Life on Mars?
Biographies of the
Compare the Planets
Other SpecialsPlanet Downloads
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The Adventure Begins . . .
The Greeks classified them as the planetae, the wanderers. The Romans gave the five they could see the names we use today: Mercury, Venus, Mars, Jupiter, and Saturn. The Chinese saw them as heavenly bureaucrats, the Mobwatese as ancestors' spirits. The most carefully maintained system, though, was that of medieval Europe. There, for centuries and centuries, planets were viewed as celestial spheres concentrically rotating around a fixed Earth, like a clockwork mechanism. Besides supposedly emanating beautiful music, the geocentric system was thought to justify the contemporary autocratic hierarchies that had "a place for everything, with everything (and every man) in its place."
This perverse system was sustained at the expense of scientific inquiry. For millennia mankind has seen the planets as it wanted to see them. Only recently, in the past three centuries, have the planets become seen as they really are: conglomerated remnants of a solar nebula elliptically orbiting around one of the billions of galactic suns.
With the gifts of science and technology, Man added Uranus, Neptune, and Pluto to the classical roster. Another was added when Earth was confessed not to be the universal keystone. Amateur astronomers, observatories, and spacecraft continually scrutinize all nine of these bodies. The results of their exploration and observation have, among other benefits, expanded the disciplines of chemistry and physics-and may one day enrich biology, too. Jupiter's atmosphere advances meteorology. Venus's clouds demonstrate the greenhouse effect. Saturn's interior reveals new states of hydrogen atoms. The planets have been laboratories for scientific theories too great to be confined to Earth. For example, Mercury's orbital discrepancies help to prove the General Theory of Relativity.
Instead of crouching in the perceived perfection of a geocentric world, languidly taking in the music of the spheres, scientists now use the planets to form more functional models of the universe. Offering clues to the fundamentals of space/time, dangling the possibility of human habitation, serving as a springboard for cutting-edge theories and technologies--maybe the planets offer us new reasons to look up at the sky in awe.
study the Martian soil.
Do you think there's life on Mars?
Big Bang: Part II? Read about the 1994 Shoemaker-Levy 9/Jupiter Collision.
See previous models of the Solar System.
What does it take to have a planet named after you? See the biographies of the planetary gods.
What probes did we launch to outer space anyway? Find out about past missions. Find out what's on the drawing board in projected missions.
Much has happened in the last 4500 years. See the timeline of special events.
We all know the planets are large, but how large are they compared with each other? Compare the planets and find out the answer to that and more!
Can't figure out just exactly how long 109 km is? We try to make the numbers more down to Earth in Relative Size of the Solar System.
Think you're a hotshot? Test yourself with our quizzes.
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