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Runliang Li
Raymond Brennan
English 1C
July 21, 2018
Final Paper
The Geocentric Model of the Earth Belief
In this century and other previous centuries, many theories have evolved on a different
phenomenon. The arguments have been brought about by scientists, philosophers, and
astronomers who are prominent in the society. The geocentric model of the solar system is one
such theory that the philosophers have presented. There are people in the community who
believe in this theory, and it has affected their cultures. The belief in this theory has created a
massive gap between those who trust in space explorers such as NASA and those who believe in
the history that the ancient philosophers presented centuries ago. The belief in pseudoscientific
theories such as this geocentric model influences the society and especially those who subscribe
to them. The typical risk of this is the culture of tending to oppose the evidence that is presented
by modern science. Such habits may lead to people who tend to resist the evidence that is
showcased by modern science which is accompanied by detailed evidence.
In Craig's book ‘The Cosmos: A Historical Perspective,' he explains that modern science
took some years to explore the solar system and to focus on the earth. The scientists have since
convinced a majority of the people that the earth is spherical. The scientists formulated the
motions that are followed by other planets, stars, and celestial bodies. The explanation led to the
rise of the geocentric model of the solar system. The model explained how the moon, sun and
other planets moved around the earth. Over a long period, by record keeping which was done by
different civilizations which were mostly originating from ancient Egypt and Babylon based
astronomers to Mediterranean astronomers, a formal system of the solar system emerged. The
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model explained that the earth was the of all other celestial bodies. After the 17th and 18th
centuries, the geocentric model was abandoned because of its inconsistencies. The heliocentric
model of the solar system was favored because it presented more verifiable evidence as
compared to the geocentric model. (pg. 14)
The initial ever recorded philosophy of the geocentric model of the solar system was
recorded in the 6th century BCE. Anaximander, a pre-Socratic philosopher, proposed a solar
system; cosmological. According to this model, the earth was cylindrical in nature, and it was
held at the center of the solar system. Anaximander explains that humans could see the sun,
moon and other celestial bodies because they were invisible holes held by wheels. Also, the
Pythagoreans started to speculate that the earth was circular based on the eclipses that were
observed. The Greeks in the 4th century BCE started to subscribe to this idea when it was
combined with the geocentric model of the solar system. (Craig, 2006)
Norris and Hetherington in their book Planetary Motions: A Historical Perspective
published in 2006 stated that Plato and Aristotle redefined the geocentric model in the 4th
century BCE. The two defined that the earth was round but maintained that the earth was the
center of the universe. The definition by Plato and Aristotle cemented well its space as the
dominant cosmological theory. (Norris, pg. 28) Plato stated that the earth was a sphere which
was stationary at the center of the universe. The other planets and stars rotated around the earth
carried in circles and spheres and arranged them in order of the distance from the earth. The
arrangement was the Moon, the Sun, Venus, Mercury, Mars, Jupiter, Saturn and then fixed stars.
Eudoxus of Cnidus later expounded the model which seemed less mythical, and he gave a more
mathematical explanation of the motions traced by the planets. The explanation emanated from
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Plato's idea of uniform circular motion. Aristotle also added that the earth was surrounded by the
other bodies which were arranged in a concentric crystalline structure.
The theory described that the other planets, sun and the moon revolved around the earth
at different uniform speeds which created the rotation of the bodies around the earth. The theory
further expressed that the earth was the heaviest of all the bodies, which explains why it moved
to the center of the universe. Water and air later formed layers around the earth. Beyond these
layers of water and air, the spheres containing the planets, suns and the moon were formed. An
observation was made that seemed to support this model of the solar system. The observation
made was that the luminosity of Venus appeared to remain constant which meant that Venus was
at an equal distance from the Earth at any given time. Later astronomers disapproved this
observation by the fact that Venus compensated for its apparent increase in size. The ancient
astronomers failed to acknowledge this because they did not have telescopes. Also, the scholars
argued that if the earth were to be moving, the position of fixed stars would have changed.
The theory falls short of some critical explanations that will align with the principles of
mathematics. It can well be understood because the ancient astronomers lacked the modern
technology to explore the solar system. The Eudoxian-Aristotlean model had its predefined
flaws. A good example is an explanation that the apparent luminous intensity of Mercury,
Jupiter, and Mars was subject to the changes in time. The theory also expressed that the motion
of Jupiter and Mars was through a retrograde motion where the planets slowed down, move
backward and then continue with their movement in the forward direction. The retrograde
motion was in contradiction of the principles of the uniform circular motion. Ptolemy, a GreekEgyptian astronomer, and mathematician emerged to standardize the aspects of the mode
developed by Aristotle and Eudoxious.
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Ptolemy also confirmed with the former theory that the earth was the center of the universe and
planets, sun and the moon revolved around it. All the stars were at a moderate distance from the
center of the earth. Ptolemy discussed that each planet was moved around the earth by two
circles which were the deferent and epicycle. The deferent accounted for the difference in
lengths of seasons while the epicycle accounted for the retrograde motion that was earlier
proposed by the Eudoxian-Aristotlean model. Ptolemy's model also failed to account for specific
observed behaviors of the planets. The model did not account for the varying size of some
planets' retrograde loop especially the Mars.
The scholars incorporated the geocentric model in Christian theology which would later
gain new power in the Medieval ages. The model turned out to be a canon in the Christianity.
Great scholars and Christian champions such as St. Thomas Aquinas accepted this theory. The
separation of the earth from other bodies which Christians referred to as ‘heavens' confirmed
with the idea of Aristotle. According to Christians, the earth was the pinnacle of God's creation.
Thus it was placed at the center. Also, the Prime Mover stated by Aristotle was perceived, by
Christians as God. (Maurice, 1989)
The Islamic community initially accepted as the cosmological model in the Middle Ages.
At the start of the 10th century BCE, more Islamic astronomers, after research started to oppose
the different aspects of Ptolemy's work. According to Bausani, an Iranian astronomer Abu 'Said
explained that the earth revolved on its axis which provided more details about the diurnal cycle
and the rotation of stars about the earth thus contradicting the Ptolemaic model. (pg. 108)
Copernicus in the 16th century began to formulate his version of the geocentric model
which he called the heliocentric model. He drew his research from great researchers and
astronomers who did not support the geocentric view. Copernicus placed the Mercury and Venus
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between the sun and the earth and consequently was able to account for their different
appearances. (Maurice et al., 2008). The model explained the retrograde motion of Mars and
Jupiter. He told that the earth astronomers do not have a fixed reference point which explained
the retrograde motion. Due to fear of condemnation from the church, Copernicus withheld his
theory until a year before he died. The invention of the telescope has since redefined the
observations that the astronomers made to the solar system, calculation of the motions of the
planets.
In the end, the cosmological model and heliocentric models succumbed because of the
technology that was invented to define the solar system. The modern space exploration
technology was used since then to observe the solar system. The models that were presented by
Ptolemy, Plato-Aristotle, and Copernicus fell short of some necessary explanations which led to
their disapproval. However, there are still communities that still subscribe to the models that
were defined by the ancient astronomers. The communities have this and such theories influence
their way of life. The communities tend to believe in the ancient way of life and also believe that
modern science is distorted. The people who originate from these communities tend to be
opposing to the scientific evidence that the modern technology and still believe in the old
theories.
The belief of the ancient theories about the models of the solar system can influence other
people. Those that believe in the modern solar system model may feel undermined because of the
use of information that has no evidence. The beliefs may have influence even on the church and
religion in general because some of the believers of Christianity still believe that the earth is the
pinnacle of God's creation. Also, the creationism theory tends to oppose other theories such as
the geocentric model because Christians believe that the earth was created out of nothing.
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However, some theories such as creationism still do not account for the model of the solar
system.
Education systems are also affected by the cosmological model theories because some of
the learners still believe in them. Also, some of the modern day scholars still believe in the
heliocentric model as presented by Copernicus. All the cosmological theories, according to the
majority of the astronomers of the 20th and 21st century have been disapproved. The
astronomers and philosophers have, besides, submitted their reasons for discontent. Maybe the
modern theories about the solar system will be approved in the future centuries when there will
be high-level technology at disposal.
The following are the errors that were identified as discussed
http://farside.ph.utexas.edu/Books/Syntaxis/Almagest/node3.html. The first thing that Ptolemy's
model failed to account for is the apparent motion that is possessed by the sun around the earth.
The model is wrong because it expresses a massive variation in the distance of the sun from the
earth. According to mathematical calculations, it is proved that the sun rotated the earth in nonuniform motion which is contrary to the Hipparchian model that Ptolemy adopted. Also in
Ptolemy's model, he failed to account for the small angular variations of the sun because it was
‘too difficult' for him. Ptolemy adopted the Hipparchian model of the solar system because the
uniform motion law favored him from Aristotle's model.
Furthermore, Ptolemy assumed the non-uniform rotation that is made by the superior
planets such as Jupiter along their epicycles. The assumption could be likened to neglecting the
earth's orbital eccentricity in comparison with the superior planets. Ptolemy just made an
approximation because the other planets have greater orbital eccentricities as compared to the
earth. The general effect of neglecting the non-uniform is the fact that there will happen a
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phenomenon of concealing of the tight couples between the apparent motions between the
planets and the sun itself. The radius vectors from the center of the epicycles to the planets
should always point to the same direction as those of the sun relative to the earth. When the nonuniform motion is neglected, the vectors of the planets will be pointing towards the mean sun
which is a fictitious body which has similar apparent motion around the earth as the sun itself.
The third flaw identified from Ptolemy's model of the solar system is related to how the
inferior planets were handled. The model suggests that in a movement from superior planets to
the minor roles, the epicycles and deferent tend to exchange the roles. The model should have
assumed the non-uniform motion performed by the epicycles at the centers of deferents of the
inferior planets. Ptolemy provided an inaccurate data of Mercury which is hard to observe using
naked eyes. The data was wrong because Mercury always appears very near to the sun in the sky.
Consequently, Ptolemy was unable to explain the apparent motion of Mercury comprehensively.
The model, therefore, was under severe scrutiny which led to its disapproval.
The last Ptolemy's error which was considered his most prominent is the treatment that he
subjected to the moon. The motion that the moon traces was not precisely known until the 20th
century. Ptolemy tried to implement a model that which was able to predict the longitude of the
lunar eclipses. The model represents a variation in the distance between the earth and the moon
by a factor of around two. The approximation was later discovered to be far off from the correct
estimate.
The believers of the cosmological theories should start to depend on the modern model of
the solar system because of the evidence that is presented and provable. The failure to trust in the
contemporary model of the solar system can bring about disunity in the nation which could
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weaken the nation's stability. Belief in the cosmological model leads to denial of verifiable truth
and trying to legitimize theories are long overdue.
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Works Cited
Bausani, A. Cosmology and Religion in Islam". Scientia/Rivista di Scienza. Pg. 108. 1973. Web.
Finocchiaro, Maurice A. The Galileo Affair: A Documentary History. Berkeley. University of
California Press. Pg. 307. 1973. Print.
Fitzpatrick, R. Ptolemy's Model of the Solar System.
. 2010. Web.
Fraser, Craig G. The Cosmos: A Historical Perspective. Pg. 14. 2006. Print
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