A model of the planetary system named after Tycho Brahe (1546-1601). Brahe was a Danish nobleman and an energetic and meticulous astronomer, who gathered much accurate data on the planets which, on his death, passed to Kepler. Brahe lived at a time when the Catholic Church was debating the admissibility of Copernicus’s theory, which put the sun at the center of the planetary system, the Earth being relegated to being just one of the planets. To fly in the face of the Church’s authority was not wise, as the case of Giordano Bruno showed: he was executed after seven years of impenitent imprisonment and torture. Tycho Brahe decided that discretion was the better part of valor and chose a middle way. His system placed the Earth at the center, with the sun and the moon traveling in orbits around it; the remainder of the planets orbited around the sun. This accepted the focal position of the Earth; in Brahes peculiar subterfuge it did remain the center of the whole system. At the same time his model gave Brahe the convenience of the Copemican system, the planets orbiting around the sun, for observation and calculation.
Although this system (the Tychonic System) is named after Tycho Brahe, he was not its first or only advocate. The system appeared in Brahe’s Progymnasmata in 1588. Two Greek astronomers, Heracleides in the fourth century B.C. and Seleucus two centuries later, had advanced a heliocentric theory. Christopher Rothmann had arrived at the same compromise a few years earlier than Brahe, and Nicholas Reimer in 1597 published De Astronomicis Hypothesibus attacking Brahe roundly for stealing his idea.