In the beginning there were only naked eye observations available from which to build a model of the Solar System. As all motion is relative, it can be difficult to discern what objects are at rest, and what objects move relative to the objects which are at rest. This difficulty partially can explain why the early geocentric model (earth at center of solar system) was used as a device to explain planetary motions - even though it was not necessarily the correct model.
Of course, this earth-centered model also plays into a cultural bias in that if you think your special in the Universe, then you necessarily occupy a special place in the Universe - that is, your located at the center of the Universe.
The early Greeks made much of this model so that's where we will begin our exploration of the solar system. In addition to this form of science, the Greeks also fundamentally examined the nature of the Universe (or Kosmos) and assumed that it had to behave in an orderly, rational, and logical manner.
One of the chief features of Early Greek Science (Hellenistic period starting around 600 BC) is its reductionist nature. That is, given a complex system (like the Earth, the weather, the Universe) the Greeks sought to reduce it down to a small number of fundamental elements out of which everything can be built. Ideally, the number of fundamental elements could be reduced to 1.
Anaximines of Miletus, c. 525 B.C. proposed that everything is made out of four elements and it was the interaction among this four elements that produces all the observed complexity in the world.
This idea would prevail for many centuries.
For example, it was believed that earth was some sort of condensation of air, while fire was some sort of emission from air. When earth condenses out of air, fire is created in the process.
This, however was not universally accepted. The most notable detractor was Democritus who postulated the existence of indestructible atoms ( from the Greek a-tome: that which cannot be cut) of an infinite variety of shapes and sizes. He imagined an infinite universe containing an infinite number of such atoms, in between the atoms there is an absolute void. Worse still is the notion that the Universe itself is a series of random interactions which can not be predicted. This runs dead counter to the requirement stated earlier that the Universe is orderly, rational, and logical
So now we have a genuine conflict: Either the Universe is random
(this is known as the atomist view)
, or the Universe is
deterministic and has predictable behavior once your know the rules. The data (e.g.
observations) support both views 
Cultural bias therefore influences
what view is adopted. Often times then data is distorted to then support this culturally
preferred view or model.
Now let's consider the kinds of naked eye observations that one could make at this time
(and still today):
For instance, at our latitude in the summer, if we look overhead we would see this pattern of
stars with some specific constellations shown:
In the winter, this pattern has clearly changed and compare the orientation of the big dipper,
the little dipper and cassiopea in this view compared to the summer view.
So then how do you make a model of the earth plus celestial sphere that is consistent with
these observations?
A stationary earth with everything else rotating around it is the most operationally simple
model and can qualitatively account for the rising and setting motion of objects, but
that's about it.
Hence it really was obvious that at times, different patterns of stars would be in the
overhead sky compared to other times and, that pattern variation was repeatable. This
would allow one to develop "constellation time", which is essentially equivalent to
a year.
careful observers would see that
the sun doesn't always rise or set in the same place each day.
even a crude timing device would show this. For instance, at the latitude of Eugene the
length of time the sun is in the sky varies by 8 hours from winter to summer. So if you
had a sand clock that say held 8 hours worth of sand , you would easily figure out that
sometimes the sun is in the sky longer than one contain's worth of stand - a lot longer.
it always does seem to
come back: This pattern most easily lends itself to a calendar where a "moon" (time between
full moons) is a unit.
more importantly, different patterns of
stars (e.g. constellations) are seen at different times of the year. This changing pattern
is really quite obvious to anyone that looks at the night sky.
Aristotle's cosmological work On The Heavens is the most influential treatise of its kind in the history of humanity. It was accepted for more that 18 centuries from its inception (around 350 B.C.) until the works of Copernicus in the early 1500s. In this work Aristotle discussed the general nature of the cosmos and certain properties of individual bodies.
The idea that all bodies, by their very nature, have a natural way of moving is central to Aristotelian
cosmology. Movement is not, he states, the result of the influence of one body on another so, no Physics !
Movement is therefore endowed to bodies. Is this science?
Some bodies naturally move in straight lines, others naturally are at rest ( but what does that mean? ). But there is yet another natural movement: the circular motion.
By logic: since to each motion there must correspond a substance, there ought to be some bodies that naturally move in circles. Aristotle then proclaims that such things are the heavenly bodies as they are made of a more exalted and perfect substance than all earthly objects.
Note the descriptors here: Exalted and Perfect
Since the stars and planets are made of this exalted substance and then move in circles, it is also natural, according to Aristotle, for these objects to be spheres also. The cosmos is then made of a central earth (which he accepted as spherical) surrounded by the moon, sun and stars all moving in circles around it. This conglomerate he called ``the world''.
Aristotle's universe is
not infinite .
Aristotle also concluded the atomists were wrong, stating that matter is in fact continuous and infinitely divisible.
(The Finite Crystalline Sphere Universe)
The initial motion of these spheres was caused by the action of a prime mover which acts on the outermost sphere of the fixed stars; somehow, however, this action is communicated to the other spheres and they move as well, but at different rates, since that is what the observations demand.
Aristotle also asserts that the world did not come into being at one point, but that it has existed, unchanged, for all eternity (it had to be that way since it was perfect .
Still, since he believed that the sphere was the most perfect of the geometrical shapes, the universe did have a center (the Earth) and its material part had an edge, which was ``gradual'' starting in the lunar and ending in the fixed star sphere.
Beyond the sphere of the stars the universe continued into the spiritual realm where material things cannot be.
This is in direct conflict with the Biblical description of creation, and an enormous amount of effort was spent by the medieval philosophers in trying to reconcile these views (and, for which, of course, no reconciliation is possible).
The crystalline sphere universe of Aristotle makes a simple prediction
all the wheels move in the same direction.
This means that any planet should always move in the same direction, with respect to the background stars (which are the coordinate system here).
Yet, the retrograde motion of Mars was well known at the time.
Mars generally moves west to east (right to left) on the background of stars. But every 780 days it goes through period of 83 days during which it moves east to west against the stars, the retrograde motion.
The retrograde period is centered around the time when Mars is in opposition - Mars is directly opposite the Sun. Thus, this phenomena could be established as repeatable and reliable after only a decade's worth of observations.
Plato gave his students a major problem to work on.
Their task was to find a geometric explanation for the apparent motion of the planets, especially the strange retrograde motion.
One key observations is that near and during the time of retrograde motion,
Mars appears significantly brighter in the sky than at other times What might this mean?
Plato and his students were, of course, also guided by the Pythagorean Paradigm. This meant that regardless of the scheme they came up with, the Earth should be at the unmoving center of the planet motions.
One student named Aristarchus violated that rule and developed a model with the Sun at the center. His model was not accepted because of the obvious observations against a moving Earth. These were all intuitive arguments based on the observation that a) one didn't feel any motion, b) the clouds in the sky didn't seem to be flying off and c) why would the center of the Universe be moving?