 
Tycho Brahe, born in 1546 was a Danish astronomer of the Renaissance, known for his comprehensive and extremly accurate astronomical observations. He was during his lifetime an astronomer, astrologer, and alchemist, and was the last major astronomer before the invention of the telescope and its use by Galileo.
With the limitations of the naked eye for making observations, he was intent on improving the existing types of instrument: the sextant and the quadrant. He designed larger versions of these, allowing him to achieve much higher accuracy. Realizing the influence of wind and the movement of buildings, he mounted his instruments underground directly on bedrock. Tycho made and recorded hundreds of observations of stellar and planetary positions, which were remarkably accurate, much more accurate than those of any predecessor or contemporary. He recorded everything he saw while completing a multitude of calculations daily. 
In 1572, Tycho noticed a completely new star in the night sky that was brighter than any star or planet. He made many observations of the phenomenon, and propsed that it must in fact be a new star. Because it had been believed since antiquity that the what was beyond the Moon's orbit was fixed and unchangeable, based on Aristotle's beliefs, other observers did not accept that what Tycho had seen was a distant star. They insisted that it must be something much closer. However, Tycho observed that the object showed no daily parallax against the background of the fixed stars. This implied that it was at least farther away than the Moon and those planets that do show such parallax. He also found that the object did not change its position relative to the fixed stars over several months, as all planets did in their periodic orbital motions. This suggested that it was not even a planet, but a fixed star beyond all the planets.  In 1573, he published a small book De nova stella, coining the term nova for a 'new star'. We now classify the star observed by Tycho as a supernova, a giant star which exploded, and which is 7,500 light-years from Earth. The publication of his discovery made him a well-known name among scientists in Europe.Astonished by the existence of a star that ought not to have been there, he devoted himself to the creation of ever more accurate instruments of measurement. His unprecedented research program turned astronomy into the first modern science, and helped launch the Scientific Revolution. Tycho Brahe was a perfectionist, and secluded on an island where he built his own observatory at Uraniborg, he had complete control over his research and was not limited by anyone else's restrictions. He could focus all of his time on his work without being questioning by anyone. The seclusion gave him the freedom to pursue his research without limitations, and paved the way for his groundbreaking discoveries in the field of astronomy. Uraniborg was one of the most advanced observatories of its time, equipped with several astronomical instruments, including quadrant instruments, sextants, and astronomical clocks. Tycho Brahe's observations and calculations at Uraniborg et him develop more accurate solar system models. He also compiled the most extensive and accurate catalog of the positions of stars up to that time. Tycho Brahe's observations and calculations laid the groundwork for astronomers in the future. Prior to his death in 1601, he was assisted for a year by Johannes Kepler, who went on to use Tycho's data to develop his own three laws of planetary motion. |