How can your Heliocentric Model even work ?

The Distance to the Sun changes over the Course of a Year by around 7 million km

that would mean that either the Sun orbits once a Year (The Heliocentric Model requires it to complete one Orbit per Day) or that immense Forces Act upon it to change it's Orbit

same Thing with all the other Planets we can observe

where do these Forces come from ?

why are they affecting everything except Earth ?

Not a problem. See Kepler's Laws of Planetary Motion.

That's not how it works

You see in the Geocentric Model the Sun goes around the Earth in one Day

but it changes it's Distance over the Course of a Year

Kepler's Laws would require an (quite large) Force acting upon these Objects to allow them to change their Orbit around Earth so they match our Observations

so why does this Force act upon Stars and Planet but doesn't spin up/accelerate Earth ?

why is is that this hypothetical Force needed for a Geocentric Model is completely different for every Object ?

it doesn't change with Mass/Distance or anything else.

Where does this Force come from ?

Why doesn't it affect us ?

Why is it apparently random ?

Kepler starts playing around with the idea that you can circumscribe a sphere around

one of these solids, and inscribe a sphere inside one of these solids--just as we

circumscribed a circle around a regular plane figure, and inscribed a circle within a

regular plane figure. But, hold on, there are only five regular solids, which means that

if you start at the outside with a sphere, and then you put in a solid, and then you put a

sphere inside that, and then a solid inside that sphere, and then a sphere inside that

solid, and you do that with the five solids, you wind up with six spheres. Fives solids

can determine the number and the sizes of six spheres, by mutual inscription and

circumscription. And, there are six planets and only five perfect solids!

Kepler played with this idea, trying to fit such a pattern of 6 spheres and the 5 perfect

solids, for years and years, doing an awful lot of mind boggling solid geometry, finding

which one should be placed where, in order that the circumscribed and inscribed

spheres should mimic the relative distances of the planets from the sun--relative

distances determinable by means of Copernicus’ theory (one of the harmonies

indicated in Chapter

. The answer was yes, you can produce a solution, if you are

Kepler, and the accuracy of the fit is 95%, that is, given the data he had on relative

orbital sizes his model had roughly a 5% error factor. (fig. 3)

So let's make this clear: Kepler thinks he has the reason why God created only five

perfect solids; it’s because He was going to create only 6 planets, and He was going to

lay down the blue print by spacing out the distances of the orbits, using this technique

of inscribing and circumscribing spheres (containing the orbits) nested within the series

of five perfect solids.

Do not think that Kepler thought these spheres or solids were up in the heavens, this is

the blueprint; there is nothing to prevent the blueprint being a 3-dimensional model, as

in figure 3. This is something like the blue print God used when he decided to make 6

(and only 6) planets and to put them at specific relative distances from the sun; the

objects in the diagram are not in the heavens--only the six planets and their variously

sized orbits are there--this stuff is on paper in Kepler's study--and stuff like that was in

God’s mind...and now they are in Kepler’s mind! When very simple and elegant results

come out of your researches, Kepler believes that you have found the truth -- the

blueprint. 5% error is good enough -- after all he’s got 100% accuracy on the number

of planets! And 95% accurate on the distances--this, then, is the Divine blueprint, and

God obviously is a Copernican! (Until, of course, somebody finds another planet--but

that will not happen for another 180 years--not a bad run.)

Kepler’s model was dismissed a long time before that--but that was only because

Natural Philosophies changed, the dominant metaphysics of the sciences changed.

The same metaphysics and the same scrupulousness produced all these results, the ones we think

are absurd, and the ones still in the text books. Kepler was working within his own

Natural Philosophical and metaphysical background and he produced that to us bizarre

insight, but to him crucial insight that God’s blueprint really had been the Copernican

one, because there exist only 5 perfect solids and 5 perfect solids space out 6 planetary

orbits only.

The first law governs the shape of the orbit and the location of the sun. The second

law governs the speed of the planet from instant to instant as it traverses that ellipse,

and if you think about it, the speed of that planet is changing from moment to moment.

So, with the two laws we have the shape of the orbit in space, and speed along the

orbit in space. A God’s eye view--not a Ptolemaic or Copernican theoretical model for

generating angular position only. It is meant as a true representation of the shape of the

orbit in space and of the real (shifting) velocity of the planet over time--a representation

that is simple and elegant, hence in Platonic metaphysical perspective, true.

In 1609 these laws were bizarre. Why ellipses? Why the sun at one focus? They seem

mystical. The areas law is even more peculiar and counter-intuitive. How does this

happen? How do planets obey such a strange rule of motion?

This, then, is Kepler’s version of Copernicanism. It does not bear much resemblance

to Copernicus’ version of Copernicanism. In fact it is unlike anything in the tradition of

theoretical astronomy going back through to Ptolemy and back to the school of Plato.

This is because the (combinations of) circles have disappeared, replaced by what

purports to be a physically true representation of the shape and dynamics of orbital

motion. Nor does this bear much relation to Newton’s version of Copernicanism to

come--although some Whig historians of science have always seen Kepler’s work as

just a step away from that of Newton.

Now the big question. How did he get these laws? Notice I avoid the term ‘discover’.

Laws of nature are not there to be discovered--they are ‘constructed’ and imposed’--just

like the theories we have been studying. We do not have the time to trace these

pathways of ‘construction’ in detail, but we shall canvass some pertinent hints and

glimpses of how the job was done.

Here is a hint about how he found the first law: The second law was first, and first law

was second, and, the second law (which was first) was not discovered, it was stated--

stipulated in view of his metaphysical commitments and aims. From the second law

(which was first) as a stipulation, he stumbled and bumbled his way to the first law

(which was second). So, the second law is an excrescence of his metaphysics and the

first law follows in step, on its basis.

But there is a problem--it is difficult to work mathematically with this law that force

(and speed) vary inversely with distance from the sun. So he makes up a

mathematically simpler, more useable approximation to it. You guessed it, this

pragmatic simplification of the force law idea is the law of areas. Kepler uses the area

law, which is just barely mathematically workable, if you don’t have calculus and are

willing to put in a lot of time calculating and breaking things up into very tiny sectors,

for practical purposes of calculating. But in strict mathematical terms it is not a

rigorously acceptable approximation of the first idea--yet he uses it. The areas law in

mathematical terms is illegitimate simplification--Kepler knew that but he was a

physical scientist, not just a mathematician.

So the Second Law is a stipulation--a mathematical simplification of the first idea of

the planet moving force, itself a metaphysically conditioned construct related to other

theory-laden ‘facts’. He didn’t ‘discover’ any fact of nature here. He had to make

decisions about concepts which depended upon his metaphysics, his earlier

metaphysically shaped ‘facts’ about the sun, and based upon the direction and aims of

his course of research. That is how the second law was intellectually constructed and

put to work.

Take a figure like Galileo, a contemporary of Kepler and one of the few other

convinced Copernicans. Does he embrace this work and integrate it with his own? Not

at all. He largely ignores Kepler. It is as though he is embarrassed by the extreme neo-

Platonism and harmony-mongering of his ‘ally’. In addition he does not seem to have

understood, or have wanted to understand Kepler’s astronomy of non-circular motions.

What did professional astronomers do? Well those who took Kepler at all seriously

tried to de-nature his results--as had been done early on with Copernicus. Most of these

workers were not Copernican anyway. If they were impressed by anything it was the

elliptical shape of the orbits. This was worth knowing, because for the first time one

could imagine the actual orbit in space. So, and this will not surprise you, they

continued to use deferents and epicycles to model and predict the motions, but they

adjusted the machinery so that the path traced out would be an ellipse. So much for

Kepler’s new idea of a causal, celestial physics!

So the great vision is torn to pieces, not taken up whole by anyone. The only person to

bring it back together again to any degree is Newton in the later 17th century, not in

Kepler’s version, but in his own particular way, so that his version is not identical to

Kepler’s.