"The great enemy of the truth is very often not the lie, deliberate, contrived and
dishonest, but the myth, persistent, persuasive and unrealistic."
In astronomy, the geocentric model or the Ptolemaic worldview of the universe is the
superseded theory that the Earth is the center of the universe and other objects go around it.
Belief in this system was common in ancient Greece. It was embraced by both Aristotle and
Ptolemy, and most, but not all, Ancient Greek philosophers assumed that the Sun, Moon,
stars, and naked eye planets circle the Earth. Similar ideas were held in ancient China.
Two common observations were believed to support the idea that the Earth is in the center of
the Universe: The first observation is that the stars, sun, and planets appear to revolve around
with the stars
each day and
to their rising
second is the
that as the
Earth is solid
and stable it
is not moving—but is at rest.
The geocentric model held sway into the early modern age; from the late 16th century
onward it was gradually replaced by the heliocentric model of Copernicus, Galileo and
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CHANGE IN THE IDEOLOGY
heliocentrism is the
theory that the Sun is
stationary and at the
center of the
universe. The word
came from the Greek.
placed the Earth at
the center. Though
discussions on the
heliocentrism date to
classical antiquity, it
was not until 1,800
years later, however,
in the 16th century,
that the Polish
a fully predictive mathematical model of a heliocentric system, which was later elaborated and
expanded by Johannes Kepler.
PEOPLE WHO MADE ALL THE DIFFERENCE
Nicolaus Copernicus (19 February 1473 – 24 May 1543) was the
first astronomer to formulate a comprehensive heliocentric
cosmology, which displaced the Earth from the center of the
universe. His epochal book, De revolutionibus orbium coelestium
(On the Revolutions of the Celestial Spheres), published in 1543
just before his death, is often regarded as the starting point of
modern astronomy and the defining epiphany that began the
scientific revolution. His heliocentric model, with the Sun at the
center of the universe, demonstrated that the observed motions of
celestial objects can be explained without putting Earth at rest in
the center of the universe. His work stimulated further scientific
investigations, becoming a landmark in the history of science that
is often referred to as the Copernican Revolution.
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Among the great polymaths of the Renaissance, Copernicus was a mathematician,
astronomer, physician, quadrilingual polyglot, classical scholar, translator, artist, Catholic
cleric, jurist, governor, military leader, diplomat and economist. Among his many
responsibilities, astronomy figured as little more than an avocation — yet it was in that field
that he made his mark upon the world.
Copernicus' major theory was published in De revolutionibus orbium coelestium (On the Revolutions
of the Celestial Spheres), in the year of his death, 1543, though he had formulated the theory several
In his Commentarial, Copernicus had summarized his system based on the seven assumptions:
1. There is no one center of all the celestial circles or spheres.
2. The center of the earth is not the center of the universe, but only of gravity and of the lunar sphere.
3. All the spheres revolve about the sun as their midpoint,
and therefore the sun is the center of the
4. The ratio of the earth's distance from the sun to the height of the firmament (outermost celestial
sphere containing the stars) is so much smaller than the ratio of the earth's radius to its distance from
the sun that the distance from the earth to the sun is imperceptible in comparison with the height of
5. Whatever motion appears in the firmament arises not from any motion of the firmament, but from
the earth's motion. The earth together with its circumjacent elements performs a complete rotation on
its fixed poles in a daily motion, while the firmament and highest heaven abide unchanged.
6. What appear to us as motions of the sun arise not from its motion but from the motion of the earth
and our sphere, with which we revolve about the sun like any other planet. The earth has, then, more
than one motion.
7. The apparent retrograde and direct motion of the planets arises not from their motion but from the
earth's. The motion of the earth alone, therefore, suffices to explain so many apparent inequalities in
Johannes Kepler (December 27, 1571 – November 15, 1630) was a German mathematician,
astronomer and astrologer, and key figure in the 17th century scientific revolution. He is best
known for his eponymous laws of planetary motion, codified by later astronomers based on
his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican Astrononomy.
They also provided one of the foundations for Isaac Newton's theory of universal gravitation.
During his career, Kepler was a mathematics teacher at a seminary school in Graz, Austria,
an assistant to astronomer Tycho Brahe, the court mathematician to Emperor Rudolf II, a
mathematics teacher in Linz, Austria, and an adviser to General Wallenstein. He also did
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fundamental work in the field of optics, invented an
improved version of the refracting telescope (the
Keplerian Telescope), and helped to legitimize the
telescopic discoveries of his contemporary Galileo
Kepler lived in an era when there was no clear
distinction between astronomy and astrology, but
there was a strong division between astronomy (a
branch of mathematics within the liberal arts) and
physics (a branch of natural philosophy). Kepler also
incorporated religious arguments and reasoning into
his work, motivated by the religious conviction that
God had created the world according to an
intelligible plan that is accessible through the natural
light of reason. Kepler described his new astronomy
as "celestial physics", as "an excursion into
Aristotle's Metaphysics", and as "a supplement to
Aristotle's On the Heavens", transforming the
ancient tradition of physical cosmology by treating astronomy as part of a universal
mathematical physics .
Johannes Kepler's first major astronomical work,
Mysterium Cosmographicum (The Cosmographic
Mystery), was the first published defense of the
Copernican system. Kepler claimed to have had
an epiphany on July 19, 1595, while teaching in
Graz, demonstrating the periodic conjunction of
Saturn and Jupiter in the zodiac; he realized that
regular polygons bound one inscribed and one
circumscribed circle at definite ratios, which, he
reasoned, might be the geometrical basis of the
universe. After failing to find a unique
arrangement of polygons that fit known
astronomical observations (even with extra
planets added to the system), Kepler began
experimenting with 3dimensional
found that each of the five Platonic solids could
be uniquely inscribed and circumscribed by
spherical orbs; nesting these solids, each encased in a sphere, within one another would
produce six layers, corresponding to the six known planets—Mercury, Venus, Earth, Mars,
Jupiter, and Saturn. By ordering the solids correctly—octahedron, icosahedron,
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dodecahedron, tetrahedron, cube—Kepler found that the spheres could be placed at intervals
corresponding (within the accuracy limits of available astronomical observations) to the
relative sizes of each planet's path, assuming the planets circle the Sun. Kepler also found a
formula relating the size of each planet's orb to the length of its orbital period: from inner to
outer planets, the ratio of increase in orbital period is twice the difference in orb radius.
However, Kepler later rejected this formula, because it was not precise enough.
Kepler thought he had revealed God's geometrical plan for the universe. Much of Kepler's
enthusiasm for the Copernican system stemmed from his theological convictions about the
connection between the physical and the spiritual; the universe itself was an image of God,
with the Sun corresponding to the Father, the stellar sphere to the Son, and the intervening
space between to the Holy Spirit. His first manuscript of Mysterium contained an extensive
chapter reconciling heliocentrism with biblical passages that seemed to support geocentrism.
With the support of his mentor Michael Maestlin, Kepler received permission from the
Tübingen university senate to publish his manuscript, pending removal of the Bible exegesis
and the addition of a simpler, more understandable description of the Copernican system as
well as Kepler's new ideas. Mysterium was published late in 1596, and Kepler received his
copies and began sending them to prominent astronomers and patrons early in 1597; it was
not widely read, but it established Kepler's reputation as a highly skilled astronomer. The
effusive dedication, to powerful patrons as well as to the men who controlled his position in
Graz, also provided a crucial doorway into the patronage system.
Though the details would be modified in light of his later work, Kepler never relinquished the
cosmology of Mysterium Cosmographicum. His subsequent
main astronomical works were in some sense only further developments of it, concerned with
finding more precise inner and outer dimensions for the spheres by calculating the
eccentricities of the planetary orbits within it. In 1621 Kepler published an expanded second
edition of Mysterium, half as long again as the first, detailing in footnotes the corrections and
improvements he had achieved in the 25 years since its first publication.
Galileo Galilei (15 February 1564 – 8 January 1642) was
an Italian physicist, mathematician, astronomer, and
philosopher who played a major role in the Scientific
Revolution. His achievements include improvements to the
telescope and consequent astronomical observations, and
support for Copernicanism. Galileo has been called the
"father of modern observational astronomy," the "father of
modern physics," the "father of science," and "the Father
of Modern Science." Stephen Hawking says, "Galileo,
perhaps more than any other single person, was
responsible for the birth of modern science."
The motion of uniformly accelerated objects, taught in nearly all high school and introductory
college physics courses, was studied by Galileo as the subject of kinematics. His
contributions to observational astronomy include the telescopic confirmation of the phases of
Venus, the discovery of the four largest satellites of Jupiter (named the Galilean moons in his
honour), and the observation and analysis of sunspots. Galileo also worked in applied science
and technology, improving compass design.
Galileo's championing of Copernicanism was controversial within his lifetime, when a large
majority of philosophers and astronomers still subscribed (at least outwardly) to the
geocentric view that the Earth is at the centre of the universe. After 1610, when he began
supporting heliocentrism publicly, he met with bitter opposition from some philosophers and
clerics, and two of the latter eventually denounced him to the Roman Inquisition early in
1615. Although he was cleared of any offence at that time, the Catholic Church nevertheless
condemned heliocentrism as "false and contrary to Scripture" in February 1616, and Galileo
was warned to abandon his support for it—which he promised to do. When he later defended
his views in his most famous work, Dialogue Concerning the Two Chief World Systems,
published in 1632, he was tried by the Inquisition, found "vehemently suspect of heresy,"
forced to recant, and spent the rest of his life under house arrest.
Galileo's contribution to astronomy are huge. He with his first practical telescope with a
resolution of over 30x saw what was till that time never seen by any human with naked eyes.
He also finally stated that earth isn't at the center of the universe and had to face the wrath of
Today even with so many advancements in the field of astronomy and space, one still can
never predict where we actually are in the universe. The sheer size of universe and its
vastness makes it impossible for us to precisely say anything. Hence where we are is only a
" Myth is, after all, the neverending