Philolaus in the 5th century BC speculated that the Earth and planets revolved daily around a central fire or sun at the center of the universe, making him one of the first to propose a non-geocentric model. Heraclides Ponticus in the 4th century BC proposed that the Earth rotates daily and developed one of the first solar system models, though it was still geocentric. Aristarchus of Samos in the 3rd century BC was the first known ancient Greek thinker to explicitly propose a heliocentric model, with the Sun at the center and the Earth and planets in circular orbits around it. However, his theory gained little traction at the time due to the dominant ge

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GREEK HELIOCENTRISM
Cosmos Adventure 3.04

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Heliocentrism
Heliocentric system, a
cosmological model in which the
Sun is assumed to lie at or near a
central point (e.g., of the solar
system or of the universe) while
the Earth and other bodies
revolve around it.
The word comes from the Greek
(helios "sun" and kentron
"center").
Historically, heliocentrism was
opposed to geocentrism, which
placed the Earth at the centre.
Wikipedia.
Heliocentric
Geocentric

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Philolaus
If the earth is a sphere, the sky had to
be a larger sphere containing it. The
celestial sphere was therefore an
interesting subject for speculation in
ancient Greece.
In the 5th century BC the Greek
Pythagorean philosopher Philolaus (c.
480 BC - c. 405 BC) and others
speculated that the Earth, the sun and
the planets were spheres revolving
daily around a mystical “central fire”
that might have worked closely as the
centre of the universe. So he was
credited with the man who first
originated the theory that the earth
was not the centre of the universe.

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Heraclides Ponticus
Sun
Earth
Moon
Mercury
Venus
Mars
Jupiter
Saturn
Heraclides Ponticus (c. 390 BC-c. 310
B.C.) was thought to be the first Greek
philosopher who proposed that the
earth rotated on its axis, from west to
east. Once every 24 hours.
He also developed the first Solar
System model, placing the planets in
order from the Earth it was is now
called the geocentric solar system
model.
Note that orbits are perfect circles
because for philosophical reasons all
things in the Heavens are "perfect").
Heraclides model became our first
cosmology of things outside the
Earth's atmosphere.

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Aristarchus’
Heliocentric Cosmology
The notion that the Earth revolves
around the Sun had been
proposed as early as the 3rd
century BC by Aristarchus (c.310–
c.230 BC) of Samos.
Aristarchus identified the “central
fire” with the Sun and proposed
an alternative model of the Solar
System placing the Sun at the
centre with the Earth and the
planets in circular orbit around it.
The Moon orbits around the Earth.
This model became the earliest
basis of the heliocentric theory.

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There might have been a few other
philosophers who speculated about
heliocentrism in early Greece and in the
post-ancient world. But the documents
are almost all lost. With the authorities
of Aristotle and Ptolemy, Aristarchus's
heliocentrism attracted little attention.

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NICHOLAS COPERNICUS’ HELIOCENTRISM
To be continued in Cosmic Adventure 3.05