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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 ...
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.
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.
The geocentric ecliptic system was the principal coordinate system for ancient astronomy and is still useful for computing the apparent motions of the Sun, Moon, and planets. [3] It was used to define the twelve astrological signs of the zodiac , for instance.
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.
In a geocentric coordinate system, this is the axis of rotation of the celestial sphere. Consequently, in ancient Greco-Roman astronomy , the axis mundi [ 1 ] is the axis of rotation of the planetary spheres within the classical geocentric model of the cosmos.
In such a system, the Sun, Moon, and stars circle a central Earth, while the five planets orbit the Sun. [16] The essential difference between the heavens (including the planets) and the Earth remained: Motion stayed in the aethereal heavens; immobility stayed with the heavy sluggish Earth. It was a system that Tycho said violated neither the ...
Files vary in the time periods they cover, ranging from a few hundred years to several thousand, and bodies they include. Data may be based on each planet's geometric center or a planetary-system barycenter. The use of Chebyshev polynomials enables highly precise, efficient calculations for any given point in time.