Geocentric model coelestium" ("On the Revolutions of the Heavenly Spheres"), which posited that the Earth and the other planets instead revolved around the Sun. The geocentric system was still held for many years afterwards, as at the time the Copernican system did not offer better predictions than the geocentric system, and it posed problems for both natural philosophy and scripture. The Copernican system was no more accurate than Ptolemy's system, because it still used circular orbits. This was not altered until Johannes Kepler postulated that they were elliptical (Kepler's first law of planetary motion). With the invention of the telescope in 1609,
Encyclopedia of the Central Intelligence Agency if he would instead be interested in writing an encyclopedia detailing the history of the CIA. Smith agreed as he felt the CIA was highly relevant to military history. "Encyclopedia of the Central Intelligence Agency" was first published in 2003 by Facts on File. It was released in both hardcover and paperback formats. An eBook edition was published the same year. Additionally an eBook was also published in 2003 in Great Britain. In the "Encyclopedia of the Central Intelligence Agency", Smith discusses and defines key concepts relating to intelligence gathering, including "clandestine mentality", a colloquial term used to characterize what