retrograde motion Concepts

4th Rock From the Sun: The Story of Mars

by Nicky Jenner · 5 Apr 2017 · 294pp · 87,986 words

‘retrograde’, has been observed for about as long as humanity has been gazing at the skies and was dutifully noted in various ancient astronomical records. Retrograde motion is simple in theory, but can be difficult to visualise. It all boils down to the motions of Earth and Mars relative to one another

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two circuits – meaning that at some point in orbit, Earth has overtaken its red rival. The moment at which it overtakes is when the apparent retrograde motion takes place. As Earth catches up with Mars, the planet seems to briefly halt. As Earth moves past Mars, briefly overtaking it on its elliptical

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halt briefly before carrying on ‘eastward’ as before. This retrograde loop usually takes Mars a couple of months to complete. Diagram explaining the phenomenon of retrograde motion – the real motion of the Earth (inner ring) and Mars (outer ring) is shown on the left, with Mars’s resulting apparent motion seen in

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two planets are orientated at that point in their orbits: sometimes it’s a loop, sometimes a zigzag, sometimes a curling ‘S’ shape. The 2003 retrograde motion, for example, zipped by as a loop-the-loop, whereas the 2005 event resembled a more jagged ‘Z’. The concept of

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retrograde motion is a good example of how the practices of astronomy and astrology are strongly intertwined and have been for centuries. Retrograde motion is a solidly scientific astronomical term. However, the concept is also used in an astrological

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ancient beliefs and symbolism, which were in turn based on what little we knew about the planet’s physical characteristics (predominantly its red colour and retrograde motion). It’s intriguing to see how our increasing knowledge about Mars feeds into the beliefs of the occult. Some witches draw a link between Mars

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with the eternal, symmetric, predictable heavens that early astronomers were picturing and attempting to explain. Mars is also a key player in the story of retrograde motion, as mentioned previously. As the planet is so close to us and obvious in our skies compared with its more distant planetary siblings, Mars’s

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played around with the velocities of the individual shells, but was unable to explain why the planets varied in brightness, or the aforementioned zigzag of retrograde motion. According to his model, each planet remained at a fixed distance from Earth, held fast by its crystal shell, and moved at a constant speed

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between any given planet and the Earth at different times in orbit. As such, epicycles could be used to explain phenomena such as Mars’s retrograde motion and varying planetary brightness without compromising on the core principles of the time (constant speeds, perfect circles, geocentrism). Ptolemy built even further on epicycles … by

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’, a point displaced to the other side of the deferent’s centre by the same distance as Earth. Both Ptolemy and Aristotle described Mars’s retrograde motion as real motion – Mars was actually moving backwards – and not apparent, as we now know to be true. An 18th-century illustration of the geocentric

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Mars here–here lunar occultations here Mars oppositions here–here, here, here, here, here, here, here, here names in other cultures here–here probes here retrograde motion here–here, here similarities to Earth here–here Mars, god of war here, here, here–here symbolism here–here Mars 1 here, here, here Mars

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cultural significance here–here, here–here natural world here psychosocial significance here Red Dragon here Red Planet here, here–here, here Rees, Martin here, here retrograde motion here–here, here Rheticus here–here Richer, Jean here RNA here–here Robinson, Kim Stanley Mars trilogy here, here–here, here robots here–here Curiosity

Big Bang

by Simon Singh · 1 Jan 2004 · 492pp · 149,259 words

in a rather haphazard manner. Occasionally, some of them even dared to stop momentarily before temporarily reversing their motion in a volte-face known as retrograde motion. These wandering rebels were the five other known planets: Mercury, Venus, Mars, Jupiter and Saturn. Indeed, the word ‘planet’ derives from the Greek planetes, meaning

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a steady manner, but we view them from a moving platform, the Earth, which is why their motion appears to be irregular. In particular, the retrograde motions exhibited by Mars, Saturn and Jupiter are easy to explain. Figure 8(a) shows a stripped-down Solar System containing just the Sun, Earth and

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Mars, as shown in Figure 8(b), looped the loop in a most peculiar manner as it orbited the Earth. Saturn and Jupiter displayed similar retrograde motions, which the Greeks also put down to looping orbits. These loopy planetary orbits were hugely problematic for the ancient Greeks, because all the orbits were

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of one astronomer, Ptolemy, who lived in Alexandria in the second century AD. Figure 8 Planets such as Mars, Jupiter and Saturn exhibit so-called retrograde motion when viewed from Earth. Diagram (a) shows a stripped-down Solar System with just the Earth and Mars orbiting (anticlockwise) around the Sun. From position

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continually moving anticlockwise around the Sun, but it appears to us that Mars is zigzagging because of the relative motions of the Earth and Mars. Retrograde motion makes perfect sense in a Sun-centred model of the universe. Diagram (b) shows how believers in an Earth-centred model perceived the orbit of

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orbits of the Sun and Moon in terms of simple circles. Then, in order to explain retrograde motions, he developed a theory of circles within circles, as illustrated in Figure 9. To generate a path with periodic retrograde motion, such as the one followed by Mars, Ptolemy proposed starting with a single circle (known

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of movements of the Sun is a result of the Earth’s revolution around it. All the planets revolve around the Sun. 7. The apparent retrograde motion of some of the planets is merely the result of our position as observer on a moving Earth. Copernicus’s axioms were spot on in

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accused them of fiddling with their theory in order to get the desired result, just as Ptolemy had fiddled with the epicycles to match the retrograde motion of Mars. In contrast, the remnant light from 300,000 years after creation could in no way be interpreted as an ad hoc postdiction. There

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spectroscopy. epicycle The small circle used in the Earth-centred Ptolemaic model of the universe, in addition to the deferent, to account for the looping retrograde motions of some planets as they moved in their supposed orbits around the Earth. ether The all-pervading substance through which light was once believed to

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not receding through space, but the expansion of space itself is causing the redshift. relativity See general theory of relativity and special theory of relativity. retrograde motion The temporary change in the apparent direction of motion of Mars, Jupiter and Saturn. It is a consequence of observing these planets from the Earth

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laws of motion 53-6, 57; orbits 49, 50, 54-6, 57,119,124, 367; phases 63-5, 66; Ptolemaic model 30-3, 31,36; retrograde motion 27,28-30, 29,38, Table 2,3; speed variations 54, 56, 57 plasma 328-30, 329, 331, 333 Plato 28 Pleiades 203-4 Poincaré

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277; special 108-16, 111, 145,298-9 religion 7, 16,18,76,306,361-2,364, 439,469,485,490; see also Catholic Church retrograde motion 27,28-30, 29,38, Table 2,3 Rheticus (G.J. von Lauchen) 40, 41, 43, 44, 53,56 Robinson, Thomas Romney 181 Römer, Ole

Coming of Age in the Milky Way

by Timothy Ferris · 30 Jun 1988 · 661pp · 169,298 words

when any given star rises and sets at a given latitude. The earth’s precessional wobble slowly alters the position of the north celestial pole. Retrograde motion results from the combined wanderings of the earth and the other planets; we overtake the outer planets like a runner on an inside track, and

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a flat earth, such a conception was quite useless when it came to determining when Mars would go into retrograde or the moon occult Jupiter. Retrograde motion of Mars occurs when Earth overtakes the more slowly moving outer planet, making Mars appear to move backward in the sky. Consequently the idea slowly

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and velocities, and by adjusting their rates of rotation and the inclination of their axes Eudoxus found that he could, more or less, account for retrograde motion and other intricacies of celestial motion. It took a total of twenty-seven spheres to do the job. This was more than Plato would have

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, 69 mean distance from the sun (est.), 123–124 measuring velocity of, 179–180 orbit of (est.), 136–137, 138 Renaissance exploration of, 47–59 retrograde motion of, 23 stellar fusion of elements and, 279–280 triangulation of the stars and, 136–137 Eccentrics of Ptolemy, 29–30 Eddington, Arthur Stanley, 38n

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problem, 121 Mars, 117 Kepler’s study of, 78–79 life on, 394 mean distance from the sun (est.), 124 measurement of diameter of, 125 retrograde motion of, 24, 25 spacecraft mission to, 371 triangulation of, 126, 130 Mason, Charles, 132–133 Mass inertia and, 193–195, 196 Newton’s laws and

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–81 mean distances from the sun (est.), 124 measuring distances via micrometry and triangulation, 125–126, 127 Newton’s laws and, 107, 117, 120–121 retrograde motion of, 23, 24, 25, 26–27 spacecraft missions to, 370, 371 transit of, 130–136 See also names of planets Plato, 19, 25–26, 27

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, 297, 337 Relativistic time dilation, 192–193 Relativity (term), 193, 285–286 See also General theory of relativity; Special theory of relativity Renaissance, 47–59 Retrograde motion of planets, 23, 24, 25 Eudoxus and, 26–27 Roman Catholic Church Copernicus’s heliocentric theory and, 67 persecution of Galileo by, 11, 84, 96

Infinite Powers: How Calculus Reveals the Secrets of the Universe

by Steven Strogatz · 31 Mar 2019 · 407pp · 116,726 words

the time they moved eastward relative to the stars, but occasionally they appeared to slow down, stop, and go backward, westward, in what astronomers called retrograde motion. Mars, for example, was seen to move in retrograde for about eleven weeks over the course of its nearly two-year circuit around the sky

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to the stars in the background. In the resulting composite, the eleven dots in the middle show Mars moving in retrograde. Today we understand that retrograde motion is an illusion. It’s caused by our vantage point on Earth as we pass the slower-moving Mars. It’s like what happens when

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observation led the ancient Greek astronomer Aristarchus to propose a sun-centered universe almost two millennia before Copernicus did. It neatly solved the riddle of retrograde motion. However, a sun-centered universe raised questions of its own. If the Earth moves, why don’t we fall off? And why do the stars

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God with patterns”: Ibid. 60 Plato had taught: Plato, Republic (Hertfordshire: Wordsworth, 1997), 240. 60 Aristotelian teaching: Asimov, Asimov’s Biographical Encyclopedia, 17–20. 61 retrograde motion: Katz, History of Mathematics, 406. 62 Aristarchus: Asimov, Asimov’s Biographical Encyclopedia, 24–25, and James Evans, “Aristarchus of Samos,” Encyclopedia Britannica, https://www.britannica

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–300 greenhouse effect, 249 Kepler on, 79 moon’s orbit, 232–33 navigation and longitude, 75 Newton and, 229, 235–36 period of, 84–85 retrograde motion, 62 tunneling phenomenon, 22 two-body problem, 237–38 eight decimal places, 295–97 Einstein, Albert, xiii, xxii, 77, 287, 289, 297, 299–301 Electric

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, 192, 196, 221 longitude, 74–75 M Madhava of Sangamagrama, 193 magic numbers, 217–18 magnetrons, 263–64 Marconi, Guglielmo, xi Mars period of, 84 retrograde motion, 61–62, 61, 62 sector areas, 82–83 Tycho and Kepler on, 78, 80 Mathematical Principles of Natural Philosophy (Newton), 229, 234, 236, 240 mathematics

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–64 differential equations, 72 God. see God “God’s book,” 294 Newton’s influence on, 239 See also Church, the Renaissance, xix, 50, 59, 92 retrograde motion, 61–62, 61, 62 Riddle of the Wall, 8–9, 8, 21–25 Riemann, Bernhard, 290 rigid bodies, 278 rule of 72, 137 rule of

To Explain the World: The Discovery of Modern Science

by Steven Weinberg · 17 Feb 2015 · 532pp · 133,143 words

the rotation of the Earth on its axis and the Earth’s revolution (like that of the other planets) around the Sun. 7. The apparent retrograde motion of the planets arises from the Earth’s motion, occurring when the Earth passes Mars, Jupiter, or Saturn, or is passed in its orbit by

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Marcellus, Claudius Marcus, 39, 71 Maria Celeste, Sister, 187 mariners, 65, 175 Marriage of Mercury and Philology, The (Martianus Capella), 124 Mars, 77, 245n apparent retrograde motion of, 90, 148 brightness of, 87 Copernicus and, 148–51 distance to, 239–40 eccentricity of orbit, 167 epicycles and, 303–6 Greeks and, 81

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, 141 medieval Europe, xiv, 26–28, 101, 124–43 Melanchthon, Philipp, 155, 157, 158, 161 mercury, 11, 198–200 Mercury, 77, 165n, 245n, 250 apparent retrograde motion of, 148 Aristotle and, 84–85 Copernicus and, 86, 148–51, 155 eccentricity of orbit, 167, 324 elongations and orbit of, 320–21 epicycles and

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; Sun; and specific concepts; individual scientists; and planets ancient mechanical model of, 71–72 apparent brightness and, 86–87, 90, 142–43, 176n–77n apparent retrograde motion and, 90, 148 Arabs and, 107, 112–14, 117–18 Aristotle and, 78–80, 83–87, 94–98, 131, 142–43 circular orbits and, 91

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and, 127–32 Newton and, 215, 218, 245–46 scientific revolution and, 146 Republic (Plato), 13, 19–20, 61 retina of the eye, 112, 174 retrograde motion of planets, 148 Rheticus, Georg Joachim, 157 Riccioli, Giovanni Battista, 184, 196, 222 Richer, Jean, 239–40 Robert Grosseteste and the Origins of Experimental Science

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, Abdus, 123 Salviati, Filippo, 186, 190 Sand Reckoner, The (Archimedes), 68–70, 300–301 Sarton, G., 369 Saturn, 77–78, 83, 85, 89, 94 apparent retrograde motion of, 148 Aristotle and, 83, 85 conjunction of Jupiter and, 159 Copernicus and, 148–49, 151 distance from Sun, 163n eccentricity of orbit, 167 epicycles

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Vatican, 128, 179, 183 velocity acceleration and, 138–39 distance and, 223, 224n momentum and, 232 Venus, 77, 245n apparent brightness, 87, 142–43 apparent retrograde motion of, 148 Aristotle on, 84–85 Copernicus and, 86, 148–51, 155 distance from Earth, 142–43 eccentricity of orbit, 167 elongations and orbit of

Life Is Simple: How Occam's Razor Set Science Free and Shapes the Universe

by Johnjoe McFadden · 27 Sep 2021

non-circular but, as well as wheeling from east to west along with the fixed stars, they frequently changed course, in what we call today retrograde motion, to move from west to east. This had not been a problem for the ancient Babylonian planets driven by capricious gods, but how do you

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model becomes an inevitable consequence of its simple alternative. Another unanticipated bonus of Copernicus’s heliocentric system was that it finally made sense of the retrograde motion of the planets Mars, Jupiter and Saturn. These normally travel east to west across the sky, along with the sun and stars, but sometimes reverse

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be moving backwards against the background, until, after we pass and view it in our rear-view mirror, it appears to be again moving forward. Retrograde motion in the heavens is the same kind of optical illusion but seen from the earth when it overtakes a slower-orbiting outer planet, such as

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Ptolemy’s. These included the elimination of terrestrial daily cycles in the orbits of the heavenly bodies, the removal of cycles needed to account for retrograde motion and an unambiguous ordering of the planets. It was these features rather than any circle count that according to Owen Gingerich, professor of astronomy and

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fifty-four. Brahe immediately gave his new assistant the challenging task of making sense of the complex orbit of Mars with its twists, turns and retrograde motion. The confident young man, convinced that he had already discovered the secret of the heavens, boasted that he would solve the problem within eight days

Firepower: How Weapons Shaped Warfare

by Paul Lockhart · 15 Mar 2021

be collected and redirected in more ways than one. Maxim discerned three ways in particular. First there was the “recoil-operated” action, which used the retrograde motion of the barrel—recoil—to power the gun’s loading and firing mechanism. Closely related to recoil operation was what is known today as a

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from the feed-belt (top, black cartridge) and the chambered cartridge that is about to be fired. “4. Moment”: The gun has now fired; the retrograde motion of the barrel from recoil throws the lock back, away from the breech. The lock-face drops, so that the fresh round just drawn from

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crew serving a mobile fieldpiece on land, recoil was most assuredly a foe. The wheels that made the gun carriage mobile also sped its violent retrograde motion, and a recoiling cannon could not be stopped safely by hand. On level, dry ground, an ordinary field gun would recoil several feet when fired

2312

by Kim Stanley Robinson · 22 May 2012 · 561pp · 167,631 words

was struck by a Mars-sized planet, creating a moon like Earth’s, called Neith; ten million years later, another impactor gave Venus its slow retrograde motion. This change in rotation slowed Neith and caused it to plunge back into Venus and merge with it. Mercury was struck by a protoplanet half

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for biological occupation. But remember, combining the Venusian year of 224 days with its daily rotation period of 243 days, you get a screwball curve (retrograde motion, sun rising in the west) in which the solar day for any particular point on the planet is 116.75 days. Tests have long since

Quicksilver

by Neal Stephenson · 9 Sep 2004 · 1,178pp · 388,227 words

imagining a phantastic heavenly axle-tree fitted out with crystalline spheres. Now we know that in fact the planets move in smooth ellipses and that retrograde motion is an illusion created by the fact that we are making our observations from a moving platform.” “Viz. the Earth.” “If we could see the

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planets from some fixed frame of reference, the retrograde motion would disappear. And you, Roger, observing Newton’s wandering trajectory—one year devising new receipts for the Philosophic Mercury, the next hard at work on

Zero: The Biography of a Dangerous Idea

by Charles Seife · 31 Aug 2000 · 233pp · 62,563 words

once more. To account for the planets’ bizarre behavior, Ptolemy added epicycles to his planetary clockwork: little circles within circles could explain the backward, or retrograde, motion of the planets (Figure 19). The power of Copernicus’s idea was in its simplicity. Instead of placing Earth at the center of the universe

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orderly succession to the throne, Henry VIII had spurned the authority of the pope, declaring himself the head of the English clergy. Figure 19: Epicycles, retrograde motion, and heliocentrism The Catholic Church had to strike back. Though it had been experimenting with other philosophies for several centuries, when threatened with schism it

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polynomials rate times time equals distance rationality, rational numbers ratios golden Rayleigh-Jeans law real numbers Rees, Martin Reformation relativity string theory and Renaissance renormalization retrograde motion Riemann, Georg Friedrich Bernhard Rig Veda Romans numerals of Scaliger, Joseph Schrödinger equation scientific revolution sets Seven Years’ War sexagesimal system Shakespeare, William Shiva Sierpinski