
	Where results make sense

Topic: Deferents

Related Topics

Ptolemaic system

Heliocentric model

Martianus Capella

Ptolemy

	Geocentric model
		In this model, a set of fifty-five concentric crystalline spheres were considered to hold the Sun, the planets, and the stars.
		These spheres (called deferents) revolved at varying velocities around the Earth to account for the rising and setting of celestial objects every day.
		The epicycles were themselves attached to the deferents; the simultaneous revolution of both sets of spheres created an occasional apparent reversal of the planets' motions across the skies of the Earth.
	www.ebroadcast.com.au /lookup/encyclopedia/ge/Geocentric.html (328 words)

	Ptolemy
		He further supposed that the distance from the Earth to the center of the deferent was equal to the distance from the center of the deferent to the equant.
		The planes of the deferents of the planets were believed to be inclined at small angles to the plane of the ecliptic, while the planes of their epicycles were inclined by equal amounts to those of the deferents, so that the planes of the epicycles would always parallel that of the ecliptic.
		The planes of the deferents of Mercury and Venus were assumed to oscillate above and below the plane of the ecliptic, and likewise the planes of their epicycles were thought to oscillate with respect to the planes of the deferents.
	abyss.uoregon.edu /~js/glossary/ptolemy.html (1349 words)

	Deferent and epicycle - Wikipedia, the free encyclopedia
		The basic elements of Ptolemaic astronomy, showing a planet on an epicycle (A) with a deferent (C) and an equant (B).
		In the Ptolemaic system of astronomy, the epicycle (literally: on the circle in Greek) was a geometric model to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planets.
		The deferent was a circle centered around a point halfway between the equant and the earth.
	en.wikipedia.org /wiki/Deferent (1085 words)

	Deferent and epicycle (via CobWeb/3.1 planetlab1.netlab.uky.edu) (Site not responding. Last check: 2007-10-14)
		In the Ptolemaic system, the planets are assumed to move in a small circle, called an epicycle, which in turn moves along a larger circle called a deferent.
		The deferent would be considered to be centered on the Earth (as the planet was believed to be in orbit around Earth...
		Half of the time, the added motion along the epicycle was eastward, in parallel with the eastward movement of the epicycle on the deference.
	deferent-and-epicycle.kiwiki.homeip.net.cob-web.org:8888 (446 words)

	Philosophers of Cosmology
		Ptolemy is known principally for his astronomical masterpiece The Almagest and for his elaboration therein of the kinematic model of deferents and epicycles, from which the tables of The Almagest were computed.
		The principal problems confronting the Greek astronomers in constructing an adequate model of the universe were: 1)the variable velocity of the planets; 2)the problem of stationary points and retrograde motion; 3)the varying distances of the planets from the earth exhibited in the changing size of the moon and changing brightness of the planets.
		By displacing the earth away from the center of the circle by using the deferents and the epicycles, the problems of varying distance and velocity is accounted for.
	ccat.sas.upenn.edu /~doors/philo.html (915 words)

	[No title]
		In other words, a planet was placed on a circular path, an ‘epicycle’, and this epicycle revolved around a larger circular path, the ‘deferent’, which ultimately circled the Earth.
		He also proposed that the distance from the earth to the centre of the deferent was equal to that of the distance between the centres of the deferent to the equant.
		Ptolemy stated that “the planes of the deferents” were inclined at small angles to this plane of the ecliptic, and the planes of the deferents epicycles were inclined by equal amounts to the deferents.
	www.astro.utoronto.ca /~bclarke/AST199M/Ptolemy.htm (2837 words)

	Simplicity (Site not responding. Last check: 2007-10-14)
		Ptolemy - there are 7 celestial objects plus the Earth 7 deferents and 20 to 40 epicycles and a sphere of the stars.
		Copernicus - there are 8 celestial objects 7 deferents and a sphere of the stars.
		A theory could be mathematically simpler because it is easier to make calculations using the theory or because it is easier to represent mathematically.
	www.bilkent.edu.tr /~cowley/Science-Inquiry/10-8-Simplicity.html (531 words)

	psr-copernicus (Site not responding. Last check: 2007-10-14)
		For example, the center of the deferent of the Earth and those of other planets do not coincide; moreover, the deferent of the Moon has its center on the Earth.
		The centers of the planets' deferents is is not the Sun.
		The Sun is at the center of the universe because it is the giver of light, the visible symbol of God.
	www.siue.edu /~evailat/psr-copernicus.html (526 words)

	Exam 2: Answer to Essay Choice C (Site not responding. Last check: 2007-10-14)
		Ptolemy's picture of the Solar System had the Earth at the center and planets orbiting about the Earth on deferents and epicycles.
		Retrograde motion under this scheme was explained by having the planet physically moving backwards in its complex orbit which combined the motion of the planet around its epicycle which in turn moved about the deferent.
		In this model, the retrograde motion of planets further from the Sun than the Earth was explained by the faster moving Earth "overtaking" a slower moving outer planet.
	www.astro.indiana.edu /~classweb/a100s0474/Exams/Exam2C.html (193 words)

	Chapter 1: The Copernican Revolution
		The planets move in circular epicycles while the centers of the epicycles move in larger circular orbits (deferents) around the Earth.
		According to Ptolemy's geocentric theory, this is explained by having each planet moving on a small circle (an epicycle) while at the same time the center of the small circle moves around the earth in a larger circle (the deferent).
		The geocentric theory of Ptolemy was very clumsy with its epicyles and deferents.
	www.pbcc.edu /faculty/sundquij/ast1002/history.htm (1604 words)

	The Universe of Aristotle and Ptolemy
		The "solution" to these problems came in the form of a mad, but clever proposal: planets were attached, not to the concentric spheres themselves, but to circles attached to the concentric spheres, as illustrated in the adjacent diagram.
		Then, the centers of the epicycles executed uniform circular motion as they went around the deferent at uniform angular velocity, and at the same time the epicyles (to which the planets were attached) executed their own uniform circular motion.
		In actual models, the center of the epicycle moved with uniform circular motion, not around the center of the deferent, but around a point that was displaced by some distance from the center of the deferent.
	csep10.phys.utk.edu /astr161/lect/retrograde/aristotle.html (757 words)

	PTOLEMY (Site not responding. Last check: 2007-10-14)
		Ptolemy's model did not adequately explain everything that observers knew to be true about the movements of the planets.
		He accounted for it by proposing a system of deferents and epicycles.
		Deferents were large circles located on the earth, and epicycles were small circles whose centers moved around the circumferences of the deferents.
	www.hamilton.k12.nj.us /secondary/reynolds/Bencivengo/MrBptolemy.htm (272 words)

	Untitled Document (Site not responding. Last check: 2007-10-14)
		For example, Mars could be seen moving in one direction in the night sky, stopping and pausing for a moment, and then traversing the other direction.
		Hipparchus, circa 150 B.C., introduced the idea of epicycles and deferents, which was a system of moving circles that rotated around stationary circles and seemingly explained the motion of planets.
		Eventually, Ptolemy developed systems of equations to describe these epicycles and deferents.
	www.facstaff.bucknell.edu /mvigeant/univ_270_03/Ryan/History.htm (451 words)

	Epicycle and Deferent Demo (via CobWeb/3.1 planetlab1.netlab.uky.edu) (Site not responding. Last check: 2007-10-14)
		For this initial display, the rotation of the deferent has been stopped by setting the "rotation ratio" to 0.
		To set the epicycle in motion around the deferent, increase the rotation ratio (the ratio of the angular velocities of the deferent to epicycle) from 0, and adjust the rate ("fast","medium" or "slow"), which governs how fast the planet's positions are drawn.
		To change the size of the epicycle, adjust "Size ratio", which is the ratio of the diameters of the deferent to the epicycle.
	www.phy.syr.edu.cob-web.org:8888 /courses/java/demos/kennett/Epicycle/Epicycle.html (274 words)

	Assignments (Site not responding. Last check: 2007-10-14)
		The planets moved in small circles called epicycles and the centers of the epicycles traced a circular orbit about the Earth called a deferent.
		Ptolemy needed 80 circles, however, to describe fully the motions of the Sun, Moon, and 5 visible planets.
		To make his model predictive, Ptolemy had to add a number of epicycles to the deferents of each planet, plus offset the center of each deferent from the Earth's position.
	www.umsl.edu /~bwilking/assign/27aug01.html (506 words)

	History of Astronomy
		The solution to retrograde motion was to use a system of circles on circles to explain the orbits of the planets called epicycles and deferents.
		The main orbit is the deferent, the smaller orbit is the epicycle.
		However, Copernicus also used circular orbits and had to resort to epicycles and deferents to explain retrograde motions.
	zebu.uoregon.edu /~js/ast121/lectures/lec02.html (1089 words)

	Solar System Models
		However, when the detailed observations of the planets in the skies is examined, the planets undergo motion which is impossible to explain in the geocentric model, a backward track for the outer planets.
		This is a key mathematical formulation because the reason Copernicus' heliocentric model has to use epicycles is due to the fact that he assumed perfectly circular orbits.
		The orbital motion of a planet is completely described by six elements: the semi-major axis, the eccentricity, the inclination, the longitude of the ascending node, the argument of the perihelion and the time of the perihelion.
	zebu.uoregon.edu /~js/ast221/lectures/lec06.html (1751 words)

	Ptolemy (Site not responding. Last check: 2007-10-14)
		The planets moved on small circular paths, called epicycles.
		The centers of these epicycles move around the earth of other circular paths, called deferents.
		The combination of the planetary motions along the epicycles and deferents produces the observed wandering of the planets among the stars, including the retrograde motion.
	astrosun.tn.cornell.edu /academics/courses/astro201/ptolemy.htm (139 words)

	Deferents (via CobWeb/3.1 planetlab1.netlab.uky.edu) (Site not responding. Last check: 2007-10-14)
		The word "deferents" uses 9 letters: D E E E F N R S T.
		Words within deferents not shown as it has more than seven letters.
		List all words starting with deferents, words containing deferents or words ending with deferents
	www.morewords.com.cob-web.org:8888 /word/deferents (145 words)

	[No title]
		Epicycles: small circles whose centers move around circumference of deferents
		Sun, moon, and planets move around circumference of own epicycle while moving around deferent.
		Nicolaus Copernicus was a polish astronomer who developed the theory that the earth is a moving planet.
	www.cobb.k12.ga.us /~lassiter/science/astronomy/first/THEORY1.HTM (568 words)

	Homework Chapter 4 (Site not responding. Last check: 2007-10-14)
		The Greek astronomers concluded that the heavens were made of perfect spheres moving at constant speed because the relative positions of the stars did not move and all the stars moved with the same angular speed of once a day around the Earth.
		Ptolemaic model had large circles called deferents and small circles centered on the deferents called epicycles.
		When the two circles moved in the same direction, the motions added.
	www.physics.fsu.edu /courses/fall98/ast1002/homework/Homework4.html (256 words)

	TDR Roundtable - Couple of issues
		When I turn my edge on you can most definitely tell a deferents and you can tell a little deferents from 1,2 and 3; not a big deferents but a little.
		You however cannot tell any deferents in power from level 3,4 or 5.
		I took my truck to dodge because when I had the truck in neutral with the clutch out at a stop light and when the light turned green and I would push the clutch it would be almost imposable to get it into any gear.
	www.turbodieselregister.com /forums/showthread.php?t=133294 (827 words)

	Astronomy 104: Lecture 4 (Slide 7) (Site not responding. Last check: 2007-10-14)
		He wrote his model down in a 13 volume set called Almagest.
		The Ptolemaic system explains the major motion of the planets with deferents and retrograde (backwards) motion with epicycles.
		The diameters and rates of the deferents and epicycles were tweaked until they fit the observed motions of the planets.
	wisp.physics.wisc.edu /astro104/lecture4/lec4g.html (154 words)

	ge187f00_questions
		(1) Ptolemy devised epicycles and deferents to explain the observed motion of the planets.
		What particular observation of planetary motion do epicycles and deferents help to explain?
		Do you think that the scientific method was applied properly in the case of the Parkfield earthquake prediction?
	www2.bc.edu /~kafka/ge187.f01/ge187f01_questions.html (970 words)

	Copernicus Ptolemy comparison handout PH490
		2) Planet moves in Epicycle on Deferent to account for retrograde motion
		b) Each of the deferents of the "outer" planets are given as the same
		the "inner" planets (Sun, Merc.,Venus) have deferents that rotate at the
	www2.una.edu /dburton/copernicus_ptolemy_comparison_ha.htm (386 words)

	Activities! (via CobWeb/3.1 planetlab1.netlab.uky.edu) (Site not responding. Last check: 2007-10-14)
		Design a portable dial using interlocking plates for a gnomon.
		Make Ptolemaic model with equants, epicycles, and deferents to explain retrograde motion.
		Construct a rainbow finder to locate a potential rainbow and to predict its apparent size.
	analyzer.depaul.edu.cob-web.org:8888 /paperplate/activities.htm (2135 words)

	Browse words starting with deferents - More Words (via CobWeb/3.1 planetlab1.netlab.uky.edu) (Site not responding. Last check: 2007-10-14)
		Browse words starting with deferents - More Words (via CobWeb/3.1 planetlab1.netlab.uky.edu)
		No longer words starting with deferents found in this word list.
		Some random words: jealous vena my khi if dhak laving
	www.morewords.com.cob-web.org:8888 /browse/deferents (66 words)

	Syracuse Physics - Educational Modules & Simulations
		The course Science and Computers, parts I (PHY307) and II (PHY308), uses applets to illustrate points in computational physics.Applets from Fall 97 include:
		Epicycle and deferents demonstration showing the Ptolemaic Earth-centered cosmology using epicycles and deferents; and the synchronous rotation of the Moon.
		Model of the solar system to show the scale of the solar system; and to illustrate Kepler's third (harmonic) law for the solar system and the Galilean satellites.
	suhep.phy.syr.edu /courses/modsim.html (317 words)

Try your search on: Qwika (all wikis)