Tycho Brahe collection

Tycho Brahe, born Tyge Ottesen Brahe on 14 December 1546 was a Danish nobleman, astronomer, and writer known for his accurate and comprehensive astronomical and planetary observations. He was born in the then Danish peninsula of Scania. Well known in his lifetime as an astronomer, astrologer and alchemist, he has been described as "the first competent mind in modern astronomy to feel ardently the passion for exact empirical facts. His observations were some five times more accurate than the best available observations at the time. Tycho worked to combine what he saw as the geometrical benefits of the Copernican system with the philosophical benefits of the Ptolemaic system into his own model of the universe, the Tychonic system. His system correctly saw the Moon as orbiting Earth, and the planets as orbiting the Sun, but erroneously considered the Sun to be orbiting the Earth. Furthermore, he was the last of the major naked-eye astronomers, working without telescopes for his observations. King Frederick II granted Tycho an estate on the island of Hven and the funding to build Uraniborg, an early research institute, where he built large astronomical instruments and took many careful measurements, and later Stjerneborg, underground, when he discovered that his instruments in Uraniborg were not sufficiently steady. After disagreements with the Danish kingin 1597, he went into exile, to Prague. He built an observatory at Benátky nad Jizerou. There, from 1600 until his death in 1601, he was assisted by Johannes Kepler, who later used Tycho's astronomical data to develop his three laws of planetary motion.

John Louis Emil Dreyer was a Danish/British astronomer. He was born in February 13, 1852 and died September 14, 1926.He won the Gold Medal of the Royal Astronomical Society in 1916 and served as the society's president from 1923 until 1925. Dreyer was also a historian of astronomy. In 1890 he published a biography of Danish astronomer Tycho Brahe, and in his later years he edited Tycho's publications and unpublished correspondence. A crater on the far side of the Moon is named after him.