Tychonic system

The Tychonic Universe. The black point at centre is the Earth, rounded by Sun and Moon. Otherwise, the Sun is rounded by five orbites, marked with planet's symbols. From: Tycho Brahe, De mundi aetherei recentioribus phaenomenis. Uranibourg, 1599.

The Tychonic Sysyem or Tychonic Universe is the model of universe developed by the observational astronomer Tycho Brahe in response to astronomical and cosmological duscussions that toke place in his time. His model incorporate many of the geometrical advantages of Copernican System (specially the movement of inner planets) without the physical and cosmological problems that came from it - in particular, the problems of a moving Earth.

In his model, the Sun place in the centre of the orbit of five planets (Mercury, Venus, Mars, Jupiter, Saturn) and the Earth remains static, being the centre of the Sun's and of Moon's orbit. Above all, remains the cristaline stellar sphere.