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<-   The mechanics of planets   ->
images/tycho-brahe.jpg
Tycho Brahé in Uraniborg Observatory : he uses very accurate visualization instruments.
Copyright : Library of Paris Observatory.

It is possible to predict the position of planets in the future or in the past with a precision of within a few centimeters, or better. Three people, Tycho Brahé, Johan Kepler and Isaac Newton have left their marks on what is now called "celestial mechanics", which is the science of computing the movements of the objects of the Solar System.

Tycho Brahé carried out observations on the position of the planets in the sky with an unequalled precision at that time (1600). These very accurate observations, over a long period of time, enabled Johan Kepler to show that the planets were moving on elliptical orbits, and that the planets were moving faster when they were closer to the star. The equations that define this movement are the three Kepler laws.