![]() ![]() ![]() He had been obsessed all his life with understanding the mysteries of the heavens, and when Brahe died in 1601 Kepler came into possession of Brahe's data (by more-or-less stealing it from Brahe's heirs). Kepler was a curious mix of the old and the new, an astrologer and a mathematician, a scientist and a mystic. In 1597 Brahe traveled to the court of Rudolph II, in Prague, and there, two years later, he met Johannes Kepler. He is considered to be the greatest of the naked-eye astronomers.īrahe was an abrasive man who treated the tenants on his island harshly (his observatory had a little jail in the basement, for "encouraging" prompt payment of rents) and when the old king died, Brahe was more-or-less evicted from Hveen. His astronomical data was by far the most accurate and the most comprehensive ever collected up to that point in history. For the next twenty years Brahe made exhaustive observations of all the planets, 777 stars, and seven comets. International attention, and in 1576, with the aid of the Danish king, he set up an observatory on the island of Hveen. A short book which Brahe wrote about the supernova of 1571 brought him to ![]() He decided that better observational data was needed. As he'd grown older, however, he'd become decidedly less impressed with the accuracy of astronomical predictions, because both the Ptolemic and the Copernican theories were often off by hours or even days. Tycho Brahe was a Danish nobleman who'd become interested in astronomy as a child, when he'd observed an eclipse and was impressed that astronomers could predict such things. In the Ptolemic model, one had to guess the distances. Also, by observing the degree of retrograde motion for each planet, one could determine the relative distance of each one from the Earth (the larger the apparent size of the "S curve", the nearer the planet). Copernicus, on the other hand, said that Mercury and Venus orbited between the Earth and Sun - whereas the other planets had orbits outside that of Earth, thus providing a much more satisfactory explanation. It was "just the way the epicycles worked out". For example, the Ptolemic model had no particular explanation for why Mercury and Venus are never seen more than a certain angular distance from the Sun, whereas Mars, Jupiter, and Saturn can be seen at any angular distance. ![]() More importantly, however, the Copernican model provided an intuitive physical picture which explained the overall features of planetary motion. (Indeed, some scholars believe that one reason Copernicus discarded the Ptolemic model was a desire to move back to a model which more closely corresponded to the classic Greek principle of uniform circular motion.) It also used only the classic epicycles, i.e., those rotating around a central axis and centered on the main circle, rather than the collections of off-axis and noncentered circles that the Ptolemic model had come to include. In view of this, what was it that (some) people found attractive about the Copernican model? Well, the Copernican model was simpler, in that it used considerably fewer epicycles than did the Ptolemic model.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |