History of physics to simplify their production. In heliocentric models of the Solar system, the Earth orbits the Sun along with other bodies in Earth's galaxy, a contradiction according to the Greek-Egyptian astronomer Ptolemy (2nd century CE; see above), whose system placed the Earth at the center of the Universe and had been accepted for over 1,400 years. The Greek astronomer Aristarchus of Samos (c.310 – c.230 BCE) had suggested that the Earth revolves around the Sun, but Copernicus' reasoning led to lasting general acceptance of this "revolutionary" idea. Copernicus' book presenting the theory ("De revolutionibus orbium coelestium", "On the Revolutions of the
History of the center of the Universe southern constellations rise higher above the horizon, and the shadow of Earth on the Moon during a lunar eclipse is round, and spheres cast circular shadows while discs generally do not. This understanding was accompanied by models of the Universe that depicted the Sun, Moon, stars, and naked eye planets circling the spherical Earth, including the noteworthy models of Aristotle (see Aristotelian physics) and Ptolemy. This geocentric model was the dominant model from the 4th century BCE until the 17th century CE. Heliocentrism, or heliocentricism, is the astronomical model in which the Earth and planets revolve around a relatively stationary