The Ptolemaic Earth-Centered System
Created September 30, 1997
- People living on the Earth feel no sensation of motion.
- The stars show no sign of parallax,
which would be expected if the Earth moved.
- The Earth was the center of the Universe.
- Celestial objects were perfect and moved perfectly uniformly on
perfectly circular paths.
- The Earth lay at the center of a
of interlaced crystaline spheres which contained the Sun, Moon, and
and which turned at constant rates.
- The model predicted the positions of the planets.
Although not very well.
- Galileo observed phases of Venus inconsistent with the
- In 1838, Bessel observed the tiny parallax of the stars due
to the Earth's orbital motion around the Sun.
- The Ptolemaic system was a valid scientific model which
explained a set of observations.
- The observations turned out to be incorrect.
- The accelerations of the moving Earth are too small to be
- The stars do show parallax. The stars are so distant that
only very precise telescopes can detect their small parallax.