Geocentric model the coordinate system in order to predict the motions of planetary bodies, though doing so may make calculations easier to perform or interpret. A geocentric coordinate system can be more convenient when dealing only with bodies mostly influenced by the gravity of the Earth (such as artificial satellites and the Moon), or when calculating what the sky will look like when viewed from Earth (as opposed to an imaginary observer looking down on the entire solar system, where a different coordinate system might be more convenient). The Ptolemaic model of the solar system held sway into the early modern age;
The Tunnel Thru the Air; Or, Looking Back from 1940 found that in March–April 1924, geocentric Jupiter was at max South declination, and geocentric Uranus in South declination during all of 1924. On July 8, 1927 geocentric Jupiter was at 0 North declination, and on May 1, 1927, geocentric Uranus was at 0 North declination. The declination of both planets was “increasing” during the 1924-1927 bull market. The Tunnel Thru the Air; Or, Looking Back from 1940 The Tunnel Thru the Air, Or, Looking Back from 1940 is a science fiction novel written by market forecaster William Delbert Gann in 1927. In the Foreword, Gann hinted that this book is