Sophia Brahe Sophia Brahe Sophia or Sophie Brahe or after marriage Sophie Thott Lange (22 September 1556 or 24 August 1559 – 1643), was a Danish horticulturalist with knowledge of astronomy, chemistry, and medicine. She assisted her brother Tycho Brahe with his astronomical observations. She was born in Knudstrup, as the youngest of ten children, to Otte Brahe "rigsråd," or advisor to the King of Denmark; and Beate Bille Brahe, leader of the royal household for Queen Sophie. Sophia's oldest brother was astronomer Tycho Brahe. Though he was both more than a decade her senior and raised in a separate household, the
Two-body problem in general relativity The Kepler problem derives its name from Johannes Kepler, who worked as an assistant to the Danish astronomer Tycho Brahe. Brahe took extraordinarily accurate measurements of the motion of the planets of the Solar System. From these measurements, Kepler was able to formulate Kepler's laws, the first modern description of planetary motion: Kepler published the first two laws in 1609 and the third law in 1619. They supplanted earlier models of the Solar System, such as those of Ptolemy and Copernicus. Kepler's laws apply only in the limited case of the two-body problem. Voltaire and Émilie du Châtelet were the