Despite all of his family problems, he was one of the most renowned astronomers ever. He was credited to a great number of achievement, some of which are listed below. He was, not surprisingly, the man who made "Kepler's Three Laws of Planetary Motion". He wrote a good number of books, too. Some examples of these are Cosmological Mystery, New Astronomy, a letter under the title of Conversation with the Starry Messenger, Observer's Report on Jupiter's Four Wandering Satelites, Dioptrice, Art of Measurement, World Harmony, and, The Rudolphine Tables. He totally dismantled Aristotle's ideas, which had been is use for 2000 years. He proved that the planet's had elliptical orbits, not circular as it was thought at the time.
Astronomy was not his only his only strong suit, though. He was also interested in his field of optics.He wrote "Dioptrice", which was a book explaining the properties of light, and how a telescope worked. Telescopes were a rather controversial invention at that time. Or, more accurately, the people who made them made suspicious claims to being the sole inventor. Galileo Galilei, another prominent astronomer, is not the one who actually invented the telescope, despite popular belief. Leonardo DaVinci invented a weakly magnifying telescope about 100 years before. Kepler, when he was able to briefly borrow a telescope, could confirm Galileo's discovery's, and was able to collect incredibly accurate data.
Today, I built a telescope of my own, out of cardboard and some basic lenses. Here are some pictures of it. The telescope works by using a lens to focus available light. The lens is curved, so this bends the object, making it look bigger. This make the object larger and brighter. The one downside to early telescopes that the image is upside-down. This rarely matters ion astronomy, as planets are round, and look mostly the same either way.
A picture of the telescope extended.
A picture I tried to take through the lens.
