Johannes Kepler was a late Renaissance astronomer/astrologer whose work helped launch Newton and the Scientific Revolution. A devout Christian, Kepler searched for ways to prove the divine within nature and the cosmos, creating models that tried to reconcile the Trinity with the movements of the planets and astro-phenomena. While Kepler had his own religious skirmishes with authorities, he managed to avoid the accusations of heresy and tragedy that enfolded is contemporary Galileo.
He also explained snowflakes.
Astronomy and Astrology: the STEM Disciplines in 1597
Back in 1600, astronomy was one of the foremost of the sciences, along with astrology. Since astrologers had to calculate planetary conditions down to precise moments of birth using limited information, their work was intricate, even if we might scoff at its purpose today. Astronomy and astrology were, therefore, branches of mathematics, which were categorized under the liberal arts. Math was sometimes taught as part of theology. Physics, which hadn’t developed much beyond Archimedes jumping out of the bathtub, was categorized as a part of “natural philosophy.”
Kepler enjoyed math as a youth and ended up studying under Tycho Brahe in Poland, as well as being imperial mathematician to the Holy Roman Emperors Rudolf II, Matthias, and Ferdinand II. If you want to know what an H.R.E. is, see G is for Ghibellines.
Defending the Heliocentric Model
Kepler was a strong defender of the heliocentric model of the universe–the one where the Sun, not the Earth, took center stage. Ptolemy in the ancient days had devised a geocentric model with Earth in the middle, around which planets and Sun rotated. Christianity liked their home being in the center. Copernicus had pressed for a model where the Sun was the significant force, a model that explained calculations far more effectively.
Kepler supported that latter version, arguing that the Sun could still represent the divine and be the central source of motive power. He compared the model to the Holy Trinity, arguing that the universe itself reflecting an image of God, with the Sun corresponding to the Father, the stellar sphere to the Son, and the intervening space between them to the Holy Spirit. He felt strongly that God had created an orderly universe, “The Word made flesh,” and his job was simply to marvel at it and describe it.
Because he was a Protestant, this didn’t get him into trouble with his wing of Christianity, as it it did with others. Still, he had some difficulty in Poland, however, since the official religions only included Catholicism and Ultraquists. (The Ultraquists fundamentally wanted the communion ceremony to include bread and wine for everybody, not just the priests. Winers didn’t have the same ring to it.) Kepler was pressed to convert to Catholicism several times, but was able to resist successfully and still keep his job, calculating horoscopes at the imperial court.
Laws of Motion
Kepler benefited by working with Tycho Brahe, who had just built a new telescope, and Galileo, who reveled in collecting data from his own telescopes. The German astronomer was more interested in the math then merely looking at the stars. He noticed that many of the models for orbits were circular, but that the numbers didn’t fit a perfect spherical pattern. He built a model showed the sphere’s of each planet’s orbits structured like an onion, but not necessarily perfect spheres.
He explained this in Mysterium Cosmographicum (The Cosmographic Mystery, 1596), the first of his dozen books that supported the Copernican system. Ultimately, he also showed that planets moved in elliptical orbits. Once he could fully determined the relationships across the planets, he was able to create the Kepler laws of planetary motion which form the basis of modern astronomy and astrophysics.
He did know Galileo and sent him a copy of Mysteruim Cosmographicum. The Italian also had concluded the Sun was the center of the world, “heart of the universe, font of light, source of heat, origin of life and cosmic motion.” But Galileo was in Italy, much closer to the inquisitors of the day, and did not fare as well with his religious masters.
In the end Kepler’s work would make other major contributions, explaining how the eye worked, inventing telescopes, and advancing the entire science of optics. Starting as an astrologer, he ended up truly aiding others to see the future.
Yeah, you saw what I did there, too.