A reluctant astrologer turned astronomer
Johann Kepler is remembered for proving that the planets revolve in an elliptical orbit around the Sun. Until then, most people believed that the whole Universe revolved around the Earth. (If you believed otherwise, you were burned at the stake!)
But our friend Johann financed his life wandering from one willing European nobleman to the next, casting horoscopes. It was Astrology that paid Kepler's bills, not Astronomy. He was obsessed with one project: proving that the five perfect solids of the ancient Greek philosopher Pythagoras could fit inside the orbits of the five visible planets. This would mean that the universe is not chaos, but in fact universal harmony exists. It was a way for Renaissance scientists to prove that God exists and He created a mathematically perfect universe.
How did Kepler prove that the planets revolve around the Sun, using the mathematics of a man with a metal nose?
In his famous book Harmonia Mundi or Music of the Spheres, Kepler raves on and on about the vibratory significance of the five perfect solids inscribed by the orbits of Mercury, Venus, Mars, Jupiter and Saturn. Then suddenly, Kepler launches into, "By the way, the planets do not revolve around the Earth, they revolve around the Sun - and here's why". Then it's back to more mysticism about philosophy and astrology.