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Hipparchus in 127 BC recognized that the equinoxes move with respect to the fixed stars and this is called a:
Precession of the equinoxes
Copernican vs. Ptolemaic world systems
On the Julian calendar by 1425 the vernal equinox fell earlier and earlier than March 21
by 1570, the equinox was falling 10 days before 21 March. The October 1582 calendar was calculated on the basis of the Copernican model of the cosmos.
If the Sun is moving to the east, does that mean the moon moves to the west?
Foundations of measurement:
then & now
Eventful moments in the Scientific Revolution
(internal history of science)
1477 earliest reprinting of Ptolemy's Geography [The map from which is below].
Ptolemy's world in the Renaissance was measurable and could readily predict a planet's observed motion and the precession of the equinox.
Ancient western cosmology stressed that our Cosmos was alive; made up of Four elements (earth, air, fire, and water).
This earth was the center of the heavens and made of base matter.
In opposition, celestial realm was dwelling place of perfect forms, this world was a reflection of the celestial quintessence.
Humans were part of a "SCALA NATURA" (a chain of being) and were divinely made (as were all things) of four material humors and an immortal soul.
Two opposed forces called gravity and
levity account for the movement of the heavens and the
1500 - 1600
Essentialism -- ""the animals and plants we observe as merely imperfect copies of the ideal or archetypal patterns defined and maintained on a supernatural plane of existence."
"Natural philosophers of the Renaissance could now appreciate the need for observation and mathematical analysis. and soon went on to transcend the theoretical achievements of the ancients."
"But even in astronomy and physics it was necessary to combine the mathematical spirit with an increased accuracy of observation."
In rejecting the geocentric or Ptolemaic model of the heavens, the precession of the equinoxes had to be explained as Galileo proposed that the Copernican model based on the heliocentric conception of the solar system.
"I have discovered four planets, neither known nor observed by any one of the astronomers before my time, which have orbits round a certain bright star, one of those previously known, like Venus & Mercury round the Sun, and are sometimes in front of it, sometimes behind it, though they never depart from it beyond certain limits."
"Now let me review the observations made by me . . . inviting the attention of all who are eager for true philosophy. . . ."
"just as the shadows in the hollows of the Earth diminish in size as the Sun rises higher, so also the spots on the Moon lose their blackness as the illuminated part grows larger and larger."
"The grandeur of such prominences and depressions in the Moon seems to surpass both in magnitude and extent the ruggedness of the Earth's surface. . . ."
1632 Pope Urban VIII wrote: "Your Galileo has ventured to meddle with things that he ought not to and with the most important and dangerous subjects which can be stirred up these days,"
Trial presided over by Ten judges; all Cardinals of the Dominican Order
According to Gerald Holton an historian at Harvard any description in order to be scientific must be refutable and be consistent across three different perspectives to have integrity such as Galileo's ideas about the earth moving around the sun, or the precession of the equinoxes:
A refutable theory is based on a set of hypotheses that can be tested and scrutinized for any and all possible facts that could undermine the theory.