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  2. Geocentric model - Wikipedia

    en.wikipedia.org/wiki/Geocentric_model

    Pages from 1550 Annotazione on Sacrobosco's De sphaera mundi, showing the Ptolemaic system. In the Ptolemaic system, each planet is moved by a system of two spheres: one called its deferent; the other, its epicycle. The deferent is a circle whose center point, called the eccentric and marked in the diagram with an X, is distant from the Earth.

  3. Barycentric and geocentric celestial reference systems

    en.wikipedia.org/wiki/Barycentric_and_geocentric...

    The geocentric system is simpler, being smaller and involving few massive objects: that coordinate system defines its center as the center of mass of the Earth itself. The barycentric system can be loosely thought of as being centered on the Sun, but the Solar System is more complicated. Even the much smaller planets exert gravitational force ...

  4. Earth-centered, Earth-fixed coordinate system - Wikipedia

    en.wikipedia.org/wiki/Earth-centered,_Earth...

    The Earth-centered, Earth-fixed coordinate system (acronym ECEF), also known as the geocentric coordinate system, is a cartesian spatial reference system that represents locations in the vicinity of the Earth (including its surface, interior, atmosphere, and surrounding outer space) as X, Y, and Z measurements from its center of mass.

  5. Cosmology - Wikipedia

    en.wikipedia.org/wiki/Cosmology

    The Almagest (the Great System). Capella's model: Martianus Capella (c. 420) Geocentric and Heliocentric The Earth is at rest in the center of the universe and circled by the Moon, the Sun, three planets and the stars, while Mercury and Venus circle the Sun. [45] Aryabhatan model Aryabhata (499) Geocentric or Heliocentric

  6. Primum Mobile - Wikipedia

    en.wikipedia.org/wiki/Primum_Mobile

    In classical, medieval, and Renaissance astronomy, the Primum Mobile (Latin: "first movable") was the outermost moving sphere in the geocentric model of the universe. [ 1 ] The concept was introduced by Ptolemy to account for the apparent daily motion of the heavens around the Earth, producing the east-to-west rising and setting of the sun and ...

  7. Copernican Revolution - Wikipedia

    en.wikipedia.org/wiki/Copernican_Revolution

    2. The Law of Equal Areas in Equal Time: A line that connects a planet to the Sun sweeps out equal areas in equal times. 3. The Law of Harmony: The time required for a planet to orbit the Sun, called its period, is proportional to long axis of the ellipse raised to the 3/2 power. The constant of proportionality is the same for all the planets.

  8. Planetary coordinate system - Wikipedia

    en.wikipedia.org/wiki/Planetary_coordinate_system

    Chart of lunar maria with lines of longitude and latitude. The prime meridian is the centre of the near side of the Moon.. A planetary coordinate system (also referred to as planetographic, planetodetic, or planetocentric) [1] [2] is a generalization of the geographic, geodetic, and the geocentric coordinate systems for planets other than Earth.

  9. Copernican principle - Wikipedia

    en.wikipedia.org/wiki/Copernican_principle

    Copernicus proposed that the motion of the planets could be explained by reference to an assumption that the Sun is centrally located and stationary in contrast to the geocentrism. He argued that the apparent retrograde motion of the planets is an illusion caused by Earth's movement around the Sun , which the Copernican model placed at the ...