The Ptolemaic system is a theory, developed by Ptolemy about 150 AD, in which a motionless Earth is said to be at the center of the universe with the Sun, Moon, and planets revolving around it in eccentric circles and epicycles; the fixed stars are attached to an outer sphere concentric with Earth. The Ptolemaic system gave the positions of the planets accurately enough for naked-eye observations, although it also made some ridiculous predictions, such as that the distance to the Moon should vary by a factor of two over its orbit. It held sway in Europe, supported by the Church of Rome, until the rise of the Copernican system.
Related categories HISTORY OF ASTRONOMY
HISTORY OF SCIENCE
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