No Einstein, no solar system
A century ago, there was a big problem, so that the use of an Einstein was not able to solve.
"Learn from yesterday, live for the moment, looking forward to tomorrow. It is important not to stop questioning."
- Albert Einstein
For thousands of years, throughout human history, the nine planets and the moon is our only cognition to the vagaries of the universe.
Stars and the Milky Way night after night, year after year, always the same, or change too little and too slow, so that human never notice to them.
Attentive person can discover, planetary motion is not arbitrary, but there are telltale signs, divided into anterograde and retrograde.
Explain their movement in the sky there are two main methods:
1, geocentric theory, namely the planet to the earth as the center.
2, heliocentric theory, namely the planet to the sun as the center, and the earth is only one of these planets.
Nearly two thousand years, is popular is the former.Copernicus is put forward in the 16th century, after the latter Galileo, Kepler's study strongly support the heliocentric theory, eventually completed by Isaac Newton of the heliocentric theory unify river's lake.
Newton's breakthrough is the greatest, because he not only describes the performance of these planets -- a elliptical orbit around the sun -- also gives the expression to the new mechanism: the law of universal gravitation.The law of gravity applies not only to the earth, also applies to all objects.
It explains why satellite orbiting the parent star, why is the comet can be repeated and often disturbed by other planets, why on earth tide, and why the planets will not interfere with each other.
The law of gravity also explains some of the more subtle phenomenon, some long before noticed the phenomenon of later generations.
If the universe contains only two point: the sun and a planet, then the orbit of the planet will be perfect oval, every week finishing moves around the sun will return to its starting point.
Under the framework of Newtonian mechanics, however, there are many quality body in the solar system, the elliptical precession or turn in its own orbit.In the middle of the 19th century, the orbit of Uranus bias led to the discovery of Neptune is because Neptune's gravity to Uranus perturbation.
In the inner solar sys