Johannes Kepler Sun photo

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Johannes Kepler

Johannes Kepler, 1571-1630

Johannes Kepler, 1571-1630




Tycho Brahe, who provided Kepler with his data while Kepler worked for him,  achieved his goal of measuring the positions of heavenly bodies to within one minute of arc. One minute of arc is 1/60th of 1°: the apparent diameter of Venus seen in the night sky at its closest approach to the Earth, or a dime seen from 200 feet away, or a quarter from across a football field! This was a tremendous feat considering that the first telescope was still decades in the future. His aim in all this had been to confirm his own picture of the universe: that the Earth was at rest, that the Sun and the Moon revolved about it, and that all the other planets revolved around the Sun—a concept halfway between those of Copernicus and Ptolemy.

By the 1600s observational astronomy had come to Europe and the spheres of Pythagoras and Aristotle were in trouble. Having been raised in the Greek geometric tradition, Kepler was very attracted to Pythagoras’ idea that the six observable planets move on six crystalline spheres within and without the five Platonic solids (top of page 81 in your personalized, fine art book, "You and the Universe"). Knowing that Tycho Brahe’s superior data would confirm or deny this, he went to work for him in 1600; but Tycho died a year later. For nine years Kepler poured over Tycho’s vast amount of data on Mars, finally discovering his three laws of motion:

1. planets move in ellipses with the Sun at a focus;

2. planets sweep out equal areas in equal times; and

3. the squares of planets’ periods are proportional to the cubes of their distance
                from the Sun.

Yet because of his indoctrination and his love for the perfect circle, Kepler resisted this tremendous discovery for years, until the data proved inescapable. It turns out, by the way, that Kepler's three experimental laws of motion can all be derived from Sir Isaac Newton's underlying three laws of force, which Newton presented in his "Principia Mathematica Philosophiae Naturalis" in 1687 (to go to Newton, click here).

This Johannes Kepler page and much of this 600-page website are excerpted from the personalized Fine Art Book You and the Universe.


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Pages 2 and 3 from your Astrology Reading in the Fine Art Book You and the Universe








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The personalized Fine Art Book You and the Universe.










© Carl Woebcke: Johannes Kepler and the history of astrology-astronomy, 1991-2017. All rights reserved.