Contains a very clear statement of the heliocentric system of astronomy.
But the explanation of this phenomenon is equally consistent with the geocentric as with the heliocentric theory of the solar system.
The coordinates thus found will in the case of a body moving around the sun be heliocentric. The reduction to the earth's centre is a problem of pure geometry.
His dissatisfaction with Ptolemaic doctrines was of early date; and he returned from Italy, where so-called Pythagorean opinions were then freely discussed, in strong and irrevocable possession of the heliocentric theory.
Although the heliocentric system is not mentioned in the treatise, a quotation in the Arenarius of Archimedes from a work of Aristarchus proves that he anticipated the great discovery of Copernicus.
HELIOCENTRIC referred to the centre of the sun (i)Xtos) as an origin, a term designating especially co-ordinates or heavenly bodies referred to that origin.
He laid the groundwork of his heliocentric theory between 1506 and 1512, and brought it to completion in De Revolutionibus Orbium Coelestium (1543) The colossal task of remaking astronomy on an inverted design was, in this treatise, virtually accomplished.
(3) In the system of heliocentric co-ordinates, the plane in which the earth moves round the sun, which is the plane of the ecliptic, is taken as the fundamental one.
Under these disadvantageous circumstances, it is scarcely surprising that the heliocentric theory, while admired as a daring speculation, won its way slowly to acceptance as a truth.
But the observations do not extend continuously throughout the year, and do not include a sufficient length of the central line on each evening to enable us to distinguish certainly the heliocentric latitude of the central line, as distinct from its apparent geocentric position.