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HUMAN IDEAS ON COSMIC DESIGN: PTOLEMY
It was a good try, but neither of these statements are true. The Earth is NOT the center of the Universe and the Earth DOES rotate--once every 24 hours, turning night into day and back again. Ptolemy was no dummy though--he was just going on the available facts of the day. That's why it's so important in science to keep testing and considering other explanations. Ptolemy himself emphasized the importance of repeated and accurate observations, and used astronomers and mathematicians to help make theory and observation match as closely as possible.
That's how he developed a model of the Universe that would last over 1300 years, all the way to the Renaissance. His great goal was to predict the changing positions of the planets and other heavenly bodies, because he figured they must have an influence on human affairs. After all, the sun and the moon certainly did, so why not the others? Ptolemy devised a model of the Universe that placed Earth at the center and the Moon, Mercury, Venus, the Sun, Mars, Jupiter, Saturn, and the stars in that order on eight concentric crystal spheres around the Earth. Each of those "planets" moved around the Earth in perfect circles, but also moved in smaller, tilted circles around the circumpherence of the circle. In that way, Ptolemy could account better for their observed motions.
Ptolemy thus ushered in another great, long-lasting scientific practice. A scientific theory must do more than just describe the world; it must accurately predict events within it. If a scientific theory can't predict, it usually isn't considered a very good one. Ptolemy was right to say that accuracy in science is very important, and it led him to develop not only a model for the Universe, but the latitude and longitude system that explorers still use today. He was as accurate and convincing as he could possibly be at the time, and numbers among the great names of science.
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Human Ideas on Cosmic Design
The SpaceTime Landscape Creating with Nature
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A few centuries later, an Egyptian astonomer named Claudius Ptolemy used Aristotlešs "if...then..." logic to try to prove the accepted model of the universe, with a motionless Earth at the center of everything. While the concept of gravity hadn't been invented yet, it was obvious that falling objects seemed to move toward the center of the Earth. Ptolemy figured that IF falling objects would probably move toward the center of the Universe, THEN the Earth must be at the center of Universe. He also figured that IF the Earth rotated, THEN anything thrown upward should not fall back to the same place (as he observed it did).