The Chandra X-ray observatory gave us this new view of SN 1604, discovered by Johannes Kepler. Once upon a time, supernova discoveries were so rare that you could name them by the year. Kepler studied at a number of universities, and was planning to be a minister when he was asked to take a teaching job. He would hold many jobs in his lifetime before becoming Tycho Brahe’s last assistant.
Tycho had discovered his own supernova in 1572. The king of Denmark gave Tycho funds and an island to build an observatory. Tycho’s many observations of planets provided Kepler with ample data to explore their motion. Kepler himself was known for his meticulous mathematical tables. Kepler believed, like Pythagoras, that mathematical relations underlie all of nature. Unlike Tycho, Kepler believed in the Copernican system, and sought to find a principle behind it.
For much of Kepler’s life, the Platonic solids fascinated him. These five shapes--tetrahedron, cube, octahedron, dodecahedron and icosahedron were known since at least the time of Pythagoras. Plato tried to relate them to the Earth and its elements. Kepler tried to explain orbits as ratios these solids, with only limited success. He had greater success with a theory of ellipses.
Starting from the principle of planets orbiting the Sun, Kepler came up with three laws:
1) Planetary orbits are elliptical with the Sun as one focus.
2) Orbits sweep out equal areas in equal amounts of time.
3) The period of a planetary orbit is proportional to its long axis raised to the 3/2 power.
These laws described the motion of planets far better than any epicycle theory. Kepler’s laws allowed him to predict the transit of Venus in 1631, providing a crucial proof. A full expalanation would come from Newton's gravity.
Galileo and Kepler kept up a correspondence. “Here at Padua,” Galileo complained in one letter, "is the principal professor of philosophy whom I have repeatedly and urgently requested to look at the moon and planets through my glass, which he pertinaciously refuses to do.” Even 400 years ago, learned minds literally refused to look at the truth. Today's cosmologists need to spend more time looking at nature. The truth can be quite beautiful.
UPDATE: New information indicates that Kepler's supernova was a Type Ia.