A New Astronomical Quranic Method for The Determination Of The Greatest Speed C
"A New Astronomical Quranic Method for The Determination Of The Greatest Speed C" is a document by Dr. Mansour HassabElnaby that purports to show that the Qur'an contains scientific foreknowledge when it "predicted" (a) the speed of light and (b) that planets exist in orbits.
The following is a sidebyside rebuttal.
"A New Astronomical Quranic Method for The Determination Of The Greatest Speed C", Dr. Mansour HassabElnaby:^{[1]}  RationalWiki: 
The speed of light is 299792.5 km/s[edit]
“”Is God's monitoring of Earth and occasional interactions with people subject to physical limitations like the speed of light? Is prayer subject to those delays? Or does prayer operate via ansible?

—everything you need to know, from "FruminousBandersnatch:^{[2]} 
Abstract: The greatest speed C, denoting the velocity of light in vacuum, is hinted at in two glorious Qur[']anic verses relating this fundamental universal contant C with the motion of the EarthMoon system. A new relativistic interpretation of this Qur[']anic relation gives C=299792.5 km/s in an extremely marvellous agreement with the accepted international value.  "Hinted at in" may be parsed as "inserted into". 
This astonishing result emphasises the unity of the physical world, the validity of the special theory of relativity and the authenticity of the Glorious Qur[']an for unbelievers.  Strangely, HassabElnaby believes that the holy book proves the science rather than vice versa. If the Qur'an disagreed with the scientific speed of light, would HassabElnaby follow the Qur'an over relativity? 
Introduction: The velocity of light[,] C[,] in [a] vacuum belongs to a small group of the fundamental constants; however, it occupies an outstanding position even within this group. First of all, it is encountered in very different branches of physics. It will come as no exaggeration if one says the story of the determination of the velocity of light is a concise history of physics. And this story has not come to an end yet. From the ancient Greeks down to the Middle ages, the speed of light was believed to be infinite. Aristotle believed that light propagates instantly!. (sic) In the eleventh century, an Arabic scientist Alhassan suggests that light travels at a finite speed. Galileo (1600) tried this speed but he [f]ailed[,] saying that light is extraordinarily rapid (l). Roemer (1676) was the first measuring (sic) C using the eclipses of the Jovian satellite Io. He obtained an inaccurate value of C (215000 km/s) because the diameter of the earth's orbit was not known exactly. Starting from 17th century, experiments show the progress of methods and techniques in the determination of the speed C as indicated in the following table (1).^{[note 1]} Froome's value was considered to be the most accurate for a long period until 1983 when the modulated laser radiation interferometers were applied for the determination of C with great precision.  Here we get a long, unnecessary history of the science of the speed of light as buildup. 
According to the US National Bureau of Standards(3): C = 299792.4574 + 0.0011 km/[s] and according to the British National Physical Laboratory C = 299792.4590 + 0.0008 km/s[.]. A basically new definition of the metre was[ ]accepted in October 1983 at the 17th General Conference on Measures and Weights (3): "The metre is the length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second". The Fixation of the value of C after the formation of the new definition of the meter does not mean yet the end of the story of this fundamental constant C. There are numerous other questions dealing with the realtion between this multifarious, enigmatic constant C and the theory of Relativity.  Indeed, the speed of light is defined as 299,792,458 m/s.^{[3]} 
Recalling the second postulate of the special theory of relativity declared by Albert Einstein (1905): "The velocity C of light in vacuum is the same in all inertial frames of reference in all directions and depend neither on the velocity of the source nor on the velocity of the observer". Pauli (4) (1958) said that the data on binary[ ]stars allowed us to consider this postulate of the constancy of the velocity of light to be almost certainly correct.  Indeed, according to Einstein, light's movement is not relative.^{[4]} 
According to Einstein's general theory of relativity (1917), the law of the constancy of the velocity C of light in vacuum can not claim any unlimited validity because the curvature of rays of light can only take place when the velocity of propagation of light varies with position!. (sic) Einstein (4) himself solved this contradiction between special and general relativity declaring in his paper written (1917): "The results of the special relativity hold only so long as we are able to disregard the influence of gravitational fields on the phenomena". This validity condition of the second postulate of special relativity is considered in the present work because the constancy of the velocity C needs absolute space (vacuum). To attain vacuum in the Einstein's sense of this word[,] it is not: (sic) sufficient just to eleminate from a volume of space every atom, molecule and particle, it is necessary also to get rid of the gravitational field. Therefore we have screened out the effect of the solar gravitational field on the geocentric orbital motion of the moon, which is considered here, according to the applied Qur[']anic equation; as a standard measure reference for evaluating the greatest cosmic speed described in the Holy Qur[']anic verses.  HassabElnaby argues that we need to eliminate the effects of gravity to get a valid result. This is incorrect, for multiple reasons. First, the gravity of the sunearthmoon system is irrelevant to this measurement, because we're not measuring the speed of light. We're measuring the movement of the moon in the earthmoon system. The gravity of the sun within the sunearthmoon system is irrelevant to the distance travelled by the moon. 
Lunar Orbital Motion described in Qur[']an: Fourteen centuries ago, the QUR[']AN (5), i.e. .the (sic) Holy Book of Islamic Religion, was directed from GOD to all humanity through Prophet Mohammad, who lived in the Arabian Peninsula. The ARAB people use the lunar system in their calculation of time. The Qur[']an addressed them in the only language they could understand without upsetting their habits. GOD (in Arabic ALLAH: the ONE and Only GOD, the CREATOR) says in the Qur[']an:
"GOD is the ONE who made the sun a shining glory and the moon a light and for her ordained mansions, so that you might know the number of years and the reckoning" (10:5) The lunar year is twelve months, the month is defined recently as the time of one revolution of the moon in its orbit around the earth.  Qur'an 10:5 (Pickthall):
HassabElnaby cites the Qur'an to prove that the Qur'an uses the lunar year. The Qur'an uses a lunar year because it was known to contemporary Arabians. This is reasonable. It's also interesting how often holy books mimic the culture they're revealed in. Aside from that, Qur'an 10:5 mentions basically nothing that HassabElnaby claims that it does. 
God hints at such orbit in the Qur[']an:
"GOD is the ONE who created the night, the day, the sun, and the moon. Each one is travelling in an orbit with its own motion" (21:33). Here an essential scientific fact is clearly stated, namely, the existence of the earth's, sun'so (sic) and moon's orbits; besides, a reference is made to the travelling of these celestial bodies in space with their own motion! A new concept had therefore been established in the Qur[']an, hundreds of years before it was discovered by modern science (67)[.] Today the concept of the lunar year is widely spread and, as we know, the moon is our nearest neighbour in space, and a companion to our planet. It is often said that the earth and moon form a twinplanet.  Qur'an 21:33 (Pickthall):
This is interesting, but not foreknowledge. 
As the moon orbits around the earth, the change in the relative positions of the moon, earth and sun cause the moon to show its phases (89). The time between consecutive new moons is 29.53 days and is called the synodic month. During this time, however, the earth, and consequently the moon's orbit, have travelled some way around the sun, so the position of the moon against the background of stars is different. [T]he time for the moon to return to the same position in the sky as viewed from earth is called the sidereal month (27.32 days) which represents the actual real net time of one revolution in the moon's orbit.  Indeed, the synodic month takes 29.530587981 days,^{[6]} the sidereal month takes 27.321661 days,^{[6]} and a day on earth takes 23 hours, 56 minutes, and 4.1 seconds.^{[7]} If, however, we are evaluating from Muhammad's time, when the Qur'an was dictated, then we should incorporate the facts that the earth's day shortens by 0.000017 s/yr, or 0.0238 s since 600^{[8]} and that the sidereal lunar month shortens by about 0.000000001857 days/yr, or 0.0000025998 days since 600.^{[9]} These differences are basically negligible; however, the failure failure of HassabElnaby to even account for this suggests a disinterest in the facts and an interest in finding Qur'anic miracles. Thus, in 600, the moon's sidereal orbit lasted 27.321661 days and the Earth's day lasted 23 hours, 56 minutes, and 4.1 seconds. 
This orbit is almost circular having an average radius r=384264 km.  Indeed, the moon orbits 384,403 km from earth.^{[10]} If, however, we are evaluating from Muhammad's time, when the Qur'an was dictated, then we should incorporate the fact that the moon regresses 0.000038 km/yr, or 0.0532 km since 600.^{[11]} This difference is basically negligible; however, the failure of HassabElnaby to even account for this suggests a disinterest in the facts and an interest in finding Qur'anic miracles. Thus, in 600, the moon orbited about 384,403 km from Earth. 
ig. 1 describes the moon's motion during a lunar month. Position A1 shows a new moon. Position B (about 2 weeks later than A1) illustrates the following full moon. Position A2 the moon has orbited the earth once (with respect to an apparently fixed star). Thus one sidereal period (27.32 days) has elapsed since position A1. The next new moon does not occur until position A3 where the moon has once again lined up with the sun. Thus one lunar synodic period (29.53 days) has elapsed since position A1.  Fig. 1 is not included in the original text, and as such cannot be included or rebutted. A pity. 
Referring to the Qur[']anic verse (10:5), we notice that it discriminates between the apparent synodic period for knowing the number of years and the real sidereal period for reckoning in scientific calculations. These two systems of measuring time are now given in the text books of Astronomy as indicated (10:5) in table 2: The aim of this work is to determine the value of the greatest speed mentioned in the following relativistic Qur[']anic verses. In these verses the sideral system should be used for both the lunar month and the terrestrial day as accurate measured periods (with respect to a distant apparently fixed star).  No such discrimination occurs. Verse 10:5 doesn't even mention lunar months, much less attempt to argue that one is *better* for use in timekeeping. The use of one over another, with absolutely no reason, again suggests a search for trinkets of foreknowledge rather than scientific learning. 
 HassabElnaby reiterates his data. 
A New Relation in the EarthMoon System: The length of the moons' orbit L and the time t of one terrestrial day are correlated in a marvellous Qur[']anic verse which describes a universal constant velocity of a certain cosmic affair as follows:
"GOD rules the cosmic affair from the heavens to the earth. Then this affair travels, to Him (i.e. through the whole universe) in one day, where the measure is one thousand years of your reckoning"[, ](32:5)[.] [T]he Qur[']anic expression "of your reckoning" leaves no doubt as to our understanding of the year as the lunar year. The verse begins with a reference to a certain "cosmic affair" which GOD creates and commands. This affair travels, permanently through the whole universe between the heavens and the Earth, so speedily that it crosses in ONE DAY a maximum distance in space equivalent to that which the moon passes during ONE THOUSAND LUNAR YEAR[S] (i.e. during 12000 Sidereal months). The question which pause[s] itself now is: what could this cosmic affair be? and what is its greatest velocity as expressed in this Qur[']anic equation?. (sic) To answer this question. The above Qur[']anic verse has been understood** in terms of the following equation: Distance crossed in vacuum by the universal cosmic affair in Osle sidereal day = length of 12000 revolutions of the moon around the earth. .:. Ct = 12000 L . where: C is the velocity of the cosmic affair, t is the time interval of one terrestrial sidereal day kefined as the time of one rotation of the earth. (sic) about its axis (relative to the stars). (sic) i.e. 23 hr, 56 min, 4.0906 sec = 86164.0906[ ]sec. ) L is the inertial distance which the moon covers in co revolution around the earth during one sidereal month i.e. L is the net length of the moon's orbit due to its own geocentric motion, without the interference of its spiral motion cause[d] by the earth's revolution around the sun, i.e. [L] is the lunar orbit length excluding the effec[t] of the solar gravitational field on the measured value.  Qur'an 32:5 (Pickthall):
First, this verse is clearly stating that, to Allah, time is meaningless. Nothing more. HassabElnaby states that the Qur'an states that "1 lightday = the distance that the moon moves in 12000 sidereal months". While "12000 sidereal months" can be gathered from the text, nowhere in the cited verse does the Qur'an mention "light" or distances. Why must we assume that Allah's "affairs" are light? And if Allah's "affairs" are light, then he certainly works slowly  it takes a whole day for the "light" to reach him, and a whole day for him to signal back! Most clearly, this verse is just saying "Allah is so incomprehensible, you can't even understand his time". Second, Qur'an 70:4 (Pickthall): After all that, the Qur'an can't even keep its story straight. Using 50,000 years makes HassabElnaby's calculation (based on 1000 years) off by about 98%. So which is the correct verse? They both are the unadulterated Word of God, aren't they? 
Let V is (sic) the measured average orbital velocity of the moon deduced from the average radius R of the lunar geocentric orbit tas (sic) measured from an orbiting earth during its heliocentric motion) .:. V = 2 Pi *R/T[.] [S]ubstituting R = 384264 km and T = the siderial lunar month = 655.71986 hr[.] .:. V = [(2 * 3.1415 * 384,264 km) / (655.71986 hr) = 3682.07 km/hr (2).]  Plugging in his numbers, HassabElnaby's math does actually return 3681.95 km/hr, or 1.0227 km/s. This is close to the 1.022 km/s velocity provided by NASA.^{[12]} Amazingly, math works. The problems only seem to arise when the Qur'an gets involved. 
Let @ (Fig. 1) is (sic) the angle travelled (sic) by the earth[]moon system around the sun during one sidereal month of period 27.321661 days. We can calculate @ if we take into consideration the period (365.25636 days) of one heliocentric revolution (1 year) of the earthmoon system (Fig. l). @ = 27.321661 * 360 [degrees] / 365.25636 = 26,92848[ degrees.] Thus @ is a characteristic constant of this system depending on uniform[ ]periods of the month and the year.  According to HassabElnaby, @ is the average degrees traveled by the moon in one sidereal month around the sun. HassabElnaby's math may be correct, but is completely irrelevant. 
Since the presence of the sun changes the geometrical properties of space and time, we must screen out its gravitational effect on the earth moon system according to the validity condition of the second postulate of special relativity, i.e. we must only consider the lunar geocentric motion without the heliocentric motion of the earthmoon system. Thus a velocity component VO = V cos(O) representing the net orbital velocity of the moon as shown in fig. (1) is introduced for calculating the net length L of the lunar orbit assuming a stationary earth. .:. L = V cos @ T [(3).] From equation (1) and (3) we get a new Qur[']anic relation for the earth moon system: [.:.] C * t = [12000 V cos(@) * T] [(4).] 1=.:. C = [12000 * V * cos(@) * T / (t)] [(5).] substituting the sidereal values of the periods t and T from table (2), the NASA value of the measured orbital lunar velocity V = 3682.07 km/hr., and the calculated [v]alue of cos@ = cos 26.92848 = 0.89157, we get the velocity of the cosmic affair from eq. 5 as expressed in the Holy Qur[']an. [.:.] C = 12000 x 3682.07 x 0.89157 x 655.71986 / 86164.0906 .:. C = 299792.5 km/s  Basically, HassabElnaby's equation boils down to this: C [Speed of light] = 1000 [Number of years in one day of god's time] * 12 [synodic lunar revolutions around the earth per years] x 3682.07 kilometers/hour [Average orbital velocity of the moon in 2001 CE in km/hr] x 0.89157 [HassabElnaby's proposed compensation factor for heliocentric gravitation] x 655.71986 hours [Length in hours of one sidereal lunar orbit transit in 2001 CE] ÷ 86164.0906 seconds [length in seconds of one day on earth today] = 299792.5 km/s Unfortunately, there are two fundamental problems here. First: HassabElnaby uses the wrong number of lunar revolutions around the earth per year. (This section ignores the 2nd problem in its calculations.) There are (roughly) 12 synodic months per year. (A synodic month occurs when the moon swings back around, slightly more than 360 degrees, and makes a new moon between the earth and the sun.^{[13]}) However, HassabElnaby multiplies the number of synodic months in a year (12) by the number of hours in a sidereal orbital transit (655). Instead, it should be the number of sidereal months in a year (13.368^{[13]}^{[14]}) by the number of hours in a sidereal orbital transit (655). This changes the equation from this: C = 1000 * 12 x 3682.07 x 0.89157 x 655.71986 ÷ 86164.0906 = 299792.5 km/s To this: C = 1000 * 13.368 x 3682.07 x 0.89157 x 655.71986 ÷ 86164.0906 = 333968.8 km/s The difference is 34176.3, or +11%. Kinda a big deal. So why did HassabElnaby include this faulty math? Either he (1) messed up, is stupid, whatever, or (2) wanted to shift the results down by 11%, so that he could get the number closer to the speed of light, and fraudulently "prove" a miracle. Second: The "compensation factor" is bullshit. (This section ignores the 1st problem in its calculations.) HassabElnaby tells us that he is going to screen out the effects of the sun's gravity. If so, why is there no value in this equation equal to the force of the sun's gravity? Instead, all we get is the cosine of the angle that the moon passes, on average, in one sidereal lunar month (cos(@)). This has asbolutely nothing to do with reality, let alone the sun's gravity. Furthermore, if HassabElnaby is trying to factor out gravity (or, as may be more likely, the orbiting motion that the moon passes in) why doesn't he bother to factor out the galaxy's gravity/orbital motion or the local supercluster's gravity/orbital motion? The answer is (1) because it doesn't make the equation fit, like the cosine of @ does. Interestingly, the equation with the cosine of @ results in exactly the speed of light, while the equation without is about 40,000 km/s off. This suggests that HassabElnaby chose the cosine of @ because it makes the equation work, rather than that the equation is a key to some cosmic mystery. Additionally, when somebody ran a nbody simulation (considered one of the best available standards for simulation) of the MoonEarthSun system with and without the Sun, they found that the speed of the moon only varied by ±0.06% in one year, depending on when the sun magically disappeared.^{[15]} By comparison, the "compensation factor" changes the value of the calculation by about 10%. 
It is very interesting to mention here the second Qur[']anic verse that hints at the same relativistic Qur[']anic equation in the earthmoon system: God Most High said:
"A day in the sight of thy Lord is like a thousand years of your reckoning" (22:47)[.] Thus both relativistic Qur[']anic equations emphasise the obtained value of the greatest speed C and show that C is a permanent absolute constant. Actually there have been no scientific evidence that the value of C can change in time as yet. The constancy principle of special relativity is confirmed in the present work, which correlates also the speed of light C in vacuum with the celestial mechanics of the earthmoon system.  Qur'an 22:47:
Again, HassabElnaby strangely argues that the Qur'an provides evidence for relativity. 
Referring to equation (4) and substituting the velocity V from eq. (2), we find that the average radius of the moon. R = [C/12000x2 Pi Cos@]*t (6) .:. "The average radius R of the lunar orbit is directly proportional to the period of one terrestrial sidereal day t.". This new law deduced in the present work is important so far as it confirms the law of conservation of momentum in the EarthMoon system. Moreover it implies the influence of the tidal effect and the gravitational change factor on the this system. According to Dirac's cosmology, the universal gravitational constant G must be variable in time! i.e., it decreases with the age Tv of the universe according to Diracs equation: G=[e^4/(m*e^2pC^3)]*1/T (7) where e the electronic charge, m and p are the masses of the the electron and proton respectively. Also according to Newtons law, the gravitational changes affect the radius R of the lunar orbit as indicated in the following equation(ll) R=[h^2/m^2*M]*1/G (8) where h is the angular momentum of the moon about the earth, m and M are the masses of the moon and earth respectively. Since h,m and M remain unchanged with time, the radius R is inversely proportional to G. Correlating the last three equations, further studies in Cosmology may be prompted and facilitated.  HassabElnaby rests on his laurels and tries to tie his new equation into other fields of physics, when the equation itself is invalid. 
Conclusion: It is both important and interesting to find a new astronomical relationZ (sic) between the radius of the lunar orbit R and the time t of one terrestrial day deduced according to a new relativistic interpretation of a cosmic Qur[']anic verse alluding to the greatest universal speed identical to the velocity C of light in vacuum. It is so awesome to find unity in the complex of phenomena, that at first sight appear to have nothing in common. This work proves the universality and constancy of the fundamental constant C as the Greatest Cosmic Speed and reveals the Glorious Qur[']an as a Holy Book worth studying with meticulous analysis since its author is the CREATOR of the Universe.  This result is denied on four grounds. First, the claimed relationship between the speed of light and the orbit of the moon is not actually present or clearly stated in the Qur'an. Second, the mathematical relationship between the speed of light and the orbit of the moon does not actually exist, unless one adds a PIDOOMA coefficient. Third, the mathematical relationship between the speed of light and the orbit of the moon does not actually exist, unless one switches synodic and sidereal months. Fourth, the Qur'an itself disagrees about how long one of Allah's years is, potentially throwing off the equation by 98%. 
Summary[edit]
Summary of claim: The Qur'an accurately describes the speed of light, which would have been unknowable.
Does this statement meet all criteria necessary for Qur'anic foreknowledge?
 Is it accurate? Yes. The speed of light is 299,792,458 m/s.
 Is it in the Qur'an? No. The Qur'an's "statement" more probably refers to the travel of angels or the length of Allah's day and contradicts other Qur'anic verses (1000 vs 50000)
 Is it precise and unambiguous? No. The Qur'an's "statement" of the speed of light could refer to the travel of angels, the length of Allah's day, or, through much mental gymnastics, the speed of light.
 It must be improbable. A statement cannot be Qur'anic foreknowledge if it reasonably could be the result of a pure guess, because foreknowledge requires a person to actually know something true, while a correct guess doesn't mean that the guesser knows anything. This also excludes contemporary beliefs that happened be true but were believed to be true without solid evidence. TLDR: Lucky guesses don't count.
 Was it unknown? No. The information "presented" in the Qur'an was present in the Bible.^{[note 3]}
Thus, this statement is not an example of Qur'anic foreknowledge.
External links[edit]
Celestial bodies have orbits[edit]
The lunar year is twelve months, the month is defined recently as the time of one revolution of the moon in its orbit around the earth. God hints at such orbit in the Quran:
"GOD is the ONE who created the night, the day, the sun, and the moon. Each one is travelling in an orbit with its own motion" (21:33). Here an essential scientific fact is stated, namely, the existence of the earth's, sun'so (sic) and moon's orbits; besides, a reference is made to the travelling of these celestial bodies in space with their own motion! A new concept had therefore been established in the Quran, hundreds of years before it was discovered by modern science[.]  Full text of Qur'an 21:33 (Pickthall):
First, the cited verse does not actually mention the Earth's orbit, and is in that respect entirely compatible with contemporary geocentrism.^{[16]}^{[17]} 
First, as noted, this isn't exactly foreknowledge.
Second, mentioning the creation of "day" apart from the creation of the sun is a bit odd for a scientific textbook, considering that one cannot exist without the other.
Third, how does one "create" the night? Much like "creating" cold, this is rather difficult to do.
Summary[edit]
Summary of claim: The Qur'an accurately states that planets have orbits, which would have been unknowable to contemporary science.
Does this statement meet all criteria necessary for Qur'anic scientific foreknowledge?
 Is it correct? Yes. Planets have orbits.
 Is it in the Qur'an? Yes. The Qur'an mentions that planets have orbits.
 Is it unambiguous? No. The Qur'an is unambiguous which planet(s) and star(s) orbit which, and offers no rebuttal to contemporary geocentrism.
 Was it outside of contemporary knowledge? No. Many people since the ancient Greeks, including contemporary Arabians, believed that other planets/stars orbited earth.
 Was it outside of contemporary technology? No. It was possible, with contemporary science, to determine that the planets of the solar system have nearfixed orbits.
Thus, this statement is not an example of Qur'anic scientific foreknowledge.
See also[edit]
External links[edit]
 Other sources:
Notes[edit]
 ↑ Table 1 does not exist in the original.
 ↑ They don't actually believe this. Whoever made the image just screwed up, funnily.
 ↑ See Psalm 90:4 and 2 Peter 3:8.
References[edit]
 ↑ HassabElnaby, Mansour. "A New Astronomical Quranic Method for The Determination Of The Greatest Speed C". IslamiCity. IslamiCity.com. n.d. Web. 31 August 2014.
 ↑ http://www.dcurbanmom.com/jforum/posts/list/90/412556.page
 ↑ See the Wikipedia article on Speed of light.
 ↑ See the Wikipedia article on Special relativity.
 ↑ http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/speed_of_light.html
 ↑ ^{6.0} ^{6.1} See the Wikipedia article on Lunar month § Terminology.
 ↑ http://www.universetoday.com/14700/howlongisadayonearth/
 ↑ http://www.scientificamerican.com/article/earthrotationsummersolstice/
 ↑ See the Wikipedia article on Lunar month § Cycle lengths.
 ↑ http://www.solarviews.com/eng/moon.htm
 ↑ Dickey, J.O. et al. Lunar laser Ranging: A Continuing Legacy of the Apollo Program. Science 265: 482490, July 22, 1994.
 ↑ http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html
 ↑ ^{13.0} ^{13.1} http://www.sumanasinc.com/webcontent/animations/content/sidereal.html
 ↑ https://www.google.com/search?sourceid=chromepsyapi2&ion=1&espv=2&ie=UTF8&q=1%20year%20%2F%2027.322%20days
 ↑ https://www.physicsforums.com/threads/earthmoonwithoutsun.381623/#post3047993
 ↑ See the Wikipedia article on Geocentric model § Ancient Greece.
 ↑ See also WikiIslam's page.