Planetary orbits


Planetary orbits

The book of science

Tom Sharp

Johannes Kepler astronomy

Planetary orbits


Foolish bird

Tycho Brahe was the last major observational astronomer to work without a telescope; he used sextants and quadrants. Galileo Galilei introduced telescopes into astronomy in 1610. Johannes Kepler tried to identify causes for his laws of planetary motion but did not have the benefit of the teachings of Galileo or Isaac Newton. Galielo taught why the planets continue to orbit with no force to push them, and Newton taught that gravity explained why orbits are elliptical. Kepler’s idea that the earth attracted the moon like a magnet came from William Gilbert.

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