Tycho Brah (February 14, 1546- October 24, 1601) was a Danish astronomer and student of Albrecht Magnus. He is considered one of the founders of modern astronomy. Brah was born on the island of Halso in Denmark. He studied law at the University of Copenhagen, but developed a strong interest in astronomy during his studies. Brahe later went to the University of Tubingen in Germany to study astronomy and began his scientific research there. His observations were very accurate, especially his observations of planetary motion, which had a significant impact on the development of astronomy at that time. Brahe also discovered a supernova and studied comets and stars. His research achievements laid the foundation for later astronomers and had a significant impact on the development of celestial mechanics and cosmic models in the future. After his death, his assistant John Kepler took over his research work.
In an alternate history, the key factor changed is that Tycho Brahe was not born, which significantly altered the course of modern astronomy.