About the Book
Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 71. Chapters: Zodiac, Celestial sphere, Geocentric model, Right ascension, Ecliptic, Sidereal year, Declination, Equatorial coordinate system, Zenith, Celestial pole, Horizon, Horizontal coordinate system, Hour angle, Azimuth, Galactic coordinate system, Ecliptic coordinate system, Circumpolar star, Celestial equator, Celestial X-ray source, Theoretical astronomy, 0, Extrasolar X-ray source astrometry, Astronomical source, Galactic quadrant, Poles of astronomical bodies, Equinox, Earth-centered inertial, Vertical direction, Plane of the ecliptic, Celestial meridiator, Nadir, Barycentric coordinates, Almucantar, Parallactic angle, SOFA, Supergalactic coordinate system, Position angle, Winter Meridian, International Celestial Reference System, Autumn Meridian, Subsolar point, Summer Meridian, Spring Meridian, International Celestial Reference Frame, Colure, Ecliptic pole, Geocentric coordinates, Astronomical coordinate systems, Gaussian year, Polar distance, Space techniques, Vertical circle, Hour circle, Celestial horizon, Prime vertical. Excerpt: Connection Timeout In astronomy, the geocentric model (also known as geocentrism, or the Ptolemaic system), is the superseded theory that the Earth is the center of the universe, and that all other objects orbit around it. This geocentric model served as the predominant cosmological system in many ancient civilizations such as ancient Greece. As such, most Ancient Greek philosophers assumed that the Sun, Moon, stars, and naked eye planets circled the Earth, including the noteworthy systems of Aristotle (see Aristotelian physics) and Ptolemy. Two commonly made observations supported the idea that the Earth was the center of the Universe. The first observation was that the stars, sun, and planets appear to revolve around the Earth each day, making the Earth the center of that system. Furth...
