Orrery on display in Kassel at the Astronomisch-Physikalisches Kabinett and in Dresden at the Mathematisch-Physikalischer Salon. In "De revolutionibus orbium coelestium", published in Nuremberg in 1543, Nicolaus Copernicus challenged the Western teaching of a geocentric universe in which the Sun revolved daily around the Earth. He observed that some Greek philosophers had proposed a heliocentric universe. This simplified the apparent epicyclic motions of the planets, making it feasible to represent the planets' paths as simple circles. This could be modelled by the use of gears. Tycho Brahe's improved instruments made precise observations of the skies (1576–1601), and from these Johannes Kepler
Gardens of the Sun Brazil attempted to return most of the planet to a "natural" state, to the extent that most of Earth's population inhabits a few megacities. The Outers, by contrast, survive by terraforming the moons of Jupiter and the other outer planets and practicing genetic engineering, which caused ideological tension with Greater Brazil, ultimately flaring into a full-scale conflict called the "Quiet War". By the time of "Gardens of the Sun", the war is over. The surviving Outers have been forced to Uranus, Neptune and Pluto as the superpowers of Earth raid the moons of Jupiter and Saturn for Outer knowledge. However,