... on Geocentrism and Heliocentrism · ... against Another Attempt to Make History of Astronomy Proof for "Heliocentrism" of Some Sort (Beyond Tychonic) · Are National Geographic conspiring with de Grasse Tyson and NASA to not mention Geocentrics?
How We Figured Out That Earth Goes Around the Sun
SciShow Space | 20.X.2015
- Pretty accurate sum of Geocentrism, up to here:
0:52 "orbitted in perfect circles"
Inessential to geocentrism per se, plus approximate truth about daily rotation.
While the concrete path of Sun around Earth is a spiral where each day get it further out or further in, further south or further north, or turning at exteremes, this is largely marginal to the movement the sun is making along with the sky around earth each day.
- 1:31 Muslim scholars were more probably Tychonian than Heliocentric.
So, they too were not questioning Geocentrism per se, but more like the exact Ptolemaic model.
As to "messy" diagrams, the "mess" is called a spirograph pattern, after a certain toy, and more technically by geometers as hypotrochoids and epitrochoids.
- 2:31 "it was just as bad as the geocentric model for predicting how the planets would move."
Thanks for admitting that.
I had a somewhat different picture, unless you add "overall".
Copernicus did make more accurate predictions than Ptolemy. But after that Geocentric Tycho Brahe made more accurate ones than Copernicus. And after that, Kepler made even more accurate ones. And he was Heliocentric, so different systems had nothing to do with it except marginally.
- 2:39 - 2:41 "and if he assumed they were ellipses, the math fit the motion of the planets, Sun, and Moon a lot better using the Heliocentric model."
Than with ellipses using the Tychonian, no.
Than with Tychonian using perfect circles, but also than with Copernican using perfect circles. Yes.
You see, Riccioli built further on Kepler and introduced ellipses into an otherwise Tychonian system. He didn't get worse off than Kepler in maths, arguably.
- 3:01 In Tychonian terms also everything in the sky is not directly orbitting Earth. Only three things are, at different speeds : fix stars at 23 h 55 min per circle, Sun at 24 h per round, Moon at 24 h 50 or 24 h 55 min per round.
All other bodies circle the Sun - and for Riccioli you just add that Io, Ganymede and so on circle Jupiter. He wrote this after the two Galileo processes.
- 3:18 How would a Geocentric model predict Venus being different distances from Earth at different fulls, or different phases at same distance?
If you mean a purely Ptolemaic one, probably so.
But a purely Ptolemaic one can be refuted by the fact that Venus sometimes passes in front of Sun, sometimes goes behind it.
You have three options from Venus observation.
- 1) Heliocentrism (either universally or locally for solar system)
- 2) Tychonian model
- 3) a model called "Egyptian model" in which Sun, Mars, Jupiter and Saturn, precisely as Moon and Fix stars go around Earth, but Venus and Mercury go in a secondary orbit around the Sun.
You do not need to pick Heliocentrism from this one.
- 3:57 In the Newtonian model, which cannot be proven by observations, how would centre of mass not be moving as planets move and how would that not disrupt orbits?
A bit before, the Church banned Heliocentrism even as a mathematical model up to 1758 - change due to "aberration" seeming to fulfil Galileo's prophecy on sooner or later finding "parallax", but even then you could not say Heliocentrism was physically true, you needed to say it was mathematically helpful in constructing a more complex Geocentric (Tychonian type Geocentric) reality. Which arguably it is.
- 4:10 "But one thing that we know one hundred percent for sure is that the geocentric model is wrong."
Depending on which one either "no you don't" or "that's a geocentric model, not the geocentric model".
- 4:14 "We've sent telescopes, probes and people up there and seen it for ourselves."
Most of us have seen from here for ourselves Geocentrism is right, if you meant visual observation from how the Earth looks from the Moon. The relativism of observation doesn't suddenly become absolute framework just because you shift the angle to an abnormal one.
If you meant geometric matchup of probes, for one there is a possibility they could be frauds, not saying as if factual that they are so, and if not, the matchup would work also in a Tychonian universe.
At the very least if the Sun has a gravitational field capable of messing with the orbit of a probe. Not sure even that is necessary.