Tycho Brahe: (14 December 1546 – 24 October 1601), born Tyge Ottesen Brahe was a Danish nobleman known for his accurate and comprehensive astronomical and planetary observations. He was born in Scania, then part of Denmark, now part of modern-day Sweden. Tycho was well known in his lifetime as an astronomer and alchemist.
Johannes Kepler 1610 - A key figure in the 17th century scientific revolution, he is best known for his eponymous laws of planetary motion, codified by later astronomers, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican Astronomy. These works also provided one of the foundations for Isaac Newton's theory of universal gravitation.
Tycho Brahe was an important astronomer, but did you know he was also a crazy partier who lost his nose in a duel? Yeah, his life was epic.
Tycho Brahe's contributions to astronomy were enormous. He not only designed and built instruments, he also calibrated them and checked their accuracy periodically. He thus revolutionized astronomical instrumentation. He also changed observational practice profoundly. Whereas earlier astronomers had been content to observe the positions of planets and the Moon at certain important points of their orbits, Tycho and his cast of assistants observed these bodies through their orbits.
Tycho Brahe is probably the most famous observational astronomer of the sixteenth-century, although is not always clear whether he is better remembered for the fact that his data provided the basis for the work of Johannes Kepler (1571-1630), or because of the more colourful aspects of his life and death.