Johannes Kepler: Everything you need to know

Jan 25, 2023
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"Kepler noticed that the farther Mars was from the sun, the more slowly the planet moved, and the closer it was to the sun, the faster Mars moved along its orbit.
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Brahe and Longomontanus... were geocentrists and dismissed Kepler's Copernicanism."

Assuming that "closer to the Sun" means physically closer in its orbit, not visually closer as seen from Earth. Hence Kepler's observation presupposes the heliocentric theory.
1) How did he measure the distance of Mars from the Sun?
2) Since Brahe and Longomontanus were geocentrists, presumably they did not buy into Kepler's observation, correct?
 
Yeah he/one would need to conceptualize the Earth as a moving/orbiting platform/observation-point, itself orbiting the Sun.
All measures and movements would be relative to that.
That would be a lot to piece together into a composit whole.
Sounds pretty remarkable to me.
 
"Kepler noticed that the farther Mars was from the sun, the more slowly the planet moved, and the closer it was to the sun, the faster Mars moved along its orbit.
This also happens with the use of epicycles and Ptolemy’s equant. Kepler was well aware of this. The problem was that this model only came close to accuracy, which is why new planetary tables had to be produced.

Tycho was convinced he could falsify the Ptolemy model by using the relative distances to Mars. Many of Tycho’s measurements were accurate to 1/2 arc min — 2x better than the eye can see.

Kepler knew he had the basis to produce an improved model — Tycho’s data for Mars.

This high confidence in Tycho carried Kepler for years in doing his heavy math calculations involving hundreds of pages of calculations.
1) How did he measure the distance of Mars from the Sun?
He didn’t, AFAIK. The transit of Venus gave us that, though there were many reasonable other approaches.
2) Since Brahe and Longomontanus were geocentrists, presumably they did not buy into Kepler's observation, correct?
I’m guessing Tycho, at least, had died before Kepler conducted measurements. I also think that Kepler’s observations were useful only after sneaking a telescope from Galileo, via a friend. [ Galileo, apparently, was concerned Kepler’s known bad eyesight would bring heavy doubt on his new invention.]
 
Kepler and all others have not noticed the Z motion. A planetary orbit is made from two rotations. Two angular accelerations. The first rotation is small, and it's pulled and stretched out.....into a larger rotation. A rotation inside of a rotation. One open rotation which forms a closed rotation. A one turn closed helix.

And until science can explain those rotations, we will never know the true dynamic of gravity.

This dynamic was finally revealed when catching a moon trajectory, and traced thru a debris field. And know one has noticed it, even today.

All intellect is surrendered for space time. An institutional science.