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What's wrong with your argument is it assumes facts that themselves need to be proven. "Stars have their own proper motions" is not an easy fact to prove, and i

What's wrong with your argument is it assumes facts that themselves need to be proven. "Stars have their own proper motions" is not an easy fact to prove, and it took a very long time for people to prove that "stars do not rotate" (I presume you mean around the earth). The sort of thing being discussed here is the sort of thing you need to do to prove that crystalline spheres do not exist. There are of course other ways to prove that crystalline spheres do not exist, but they are things like the existence of black holes or the speed of light. And in general, all these sorts of things require a much broader knowledge base/trust in our current understanding to prove the idea that the earth rotates. This article is saying that if you can prove how a gyroscope works (itself requiring proof of the Conservation of Angular Momentum), you can show that the earth rotates. Which is ultimately a much simpler thing to prove than things about the nature of the stars themselves.

nyc111 5y ago
We know stars are distributed in various distances, this we know by observation. If not the earth but the stars rotate we must assume that billions of crystal spheres at different distances somehow rotate in exact coordination to trace the star trails that we observe. I don’t think there is such a huge “conspiracy” of crystal spheres to fool us.
- codethief 5y ago
  > We know stars are distributed in various distances, this we know by observation. How do we know? Establishing the cosmic distance ladder requires far more elaborate tools than the ones discussed here (Special and General Relativity, for instance) and the necessary measurements and observations also presume in one way or another that Earth is rotating. Even if you're only talking about stars in our immediate neighborhood for which a distance measurement merely needs the parallax effect (instead of SR or GR): In this case the parallax effects literally rests on the rotation of Earth and its orbit around the sun.
  - nyc111 5y ago
    > the necessary measurements and observations also presume in one way or another that Earth is rotating. Yes, the lack of star parallaxes were the main argument offered by Tycho Brahe against a moving earth theory. When star parallaxes were observed the motion of earth was accepted. The way I understand it, to measure star parallaxes the earth must move. This is not an assumption, there is no circular reasoning. And we observe different parallaxes for different stars, meaning that stars are not all on the same distance from earth. I don't know if this is a trend like flat earthers to say that all stars are the same distance from the center of the universe? > In this case the parallax effects literally rests on the rotation of Earth and its orbit around the sun. So, this way you prove that the earth moves and stars have different parallaxes and are not all attached to a crystal sphere. I don't see a problem here.
    - sandworm101 5y ago
      Stars can still have parallaxes while bolted to the spheres. Maybe the spheres themselves wobble a little. Maybe the motion of the sun around the earth imparts a slight motion to closer spheres. The fixed stars are obviously on spheres far enough away that the sun doesn't shake them.
    - throw0101a 5y ago
      > Yes, the lack of star parallaxes were the main argument offered by Tycho Brahe against a moving earth theory. Much earlier than Brahe. Aristotle in De Caelo (Book II, part 14): > The earth, then, also, whether it move about the centre or as stationary at it, must necessarily move with two motions. But if this were so, there would have to be passings and turnings of the fixed stars. Yet no such thing is observed. The same stars always rise and set in the same parts of the earth. * http://classics.mit.edu/Aristotle/heavens.2.ii.html http://classics.mit.edu/Aristotle/heavens.2.ii.html * https://en.wikipedia.org/wiki/On_the_Heavens https://en.wikipedia.org/wiki/On_the_Heavens
    - codethief 5y ago
      > This is not an assumption, there is no circular reasoning. Of course it is an assumption. A star moving across the sky is not a proof by any means. > And we observe different parallaxes for different stars, meaning that stars are not all on the same distance from earth. No, we don't measure different parallaxes for different stars. We measure different trajectories for different stars across our night sky and then, using the assumption that Earth rotates and that it is on an orbit around the sun, we conclude that there must be a parallax effect involved in the observed trajectory of the star which we can then use to estimate its distance to us. > So, this way you prove that the earth moves and stars have different parallaxes and are not all attached to a crystal sphere. I don't see a problem here. To see that what you're referring to as "proof" is no proof at all, consider that Ptolemy's epicycles (i.e. the elaborate version of the crystal spheres) are just a Fourier series and can therefore be used to describe any periodic movement across the sky. (Without you having to know anything about whether Earth rotates or not.) For a very impressive example see https://m.youtube.com/watch?v=QVuU2YCwHjw https://m.youtube.com/watch?v=QVuU2YCwHjw .
nyc111 5y ago
“Stars have their own proper motions" is not an easy fact to prove. . .” No, proper motions are well known, https://www.britannica.com/science/proper-motion#:~:text=proper%20motion%2C%20in%20astronomy%2C%20the,distant%20background%20stars%20or%20galaxies https://www.britannica.com/science/proper-motion#:~:text=pro.... So we must further assume that a star attached to a crystal sphere will have a separate motion which also need to be explained.
- IanCal 5y ago
  It's well known that the earth rotates too though.
- sandworm101 5y ago
  >> a star attached to a crystal sphere will have a separate motion Two spheres. Proper motion can be explained completely if we allow each star to exist on its own crystal sphere. Layers of spheres could also extend great distances. Maybe the universe is vast, but it is all spheres. What does disprove spheres are collisions of objects having different proper motions.
  - nyc111 5y ago
    > Two spheres. Proper motion can be explained completely if we allow each star to exist on its own crystal sphere. Wow! I can believe we are discussing in the age of Hubble space telecope and Webb etc. the existence of crystal spheres and how they can explain motions of stars. I don't believe crystal spheres exist but I respect your belief in them. To me they are an unnecessary and cumbursome explanation.
    - FredPret 5y ago
      Nobody believes in crystal spheres. The point is they are not so trivial to disprove.
    - sandworm101 5y ago
      As cumbersome as unobserved massive particles representing the majority of matter in the universe?
littlestymaar 5y ago
> This article is saying that if you can prove how a gyroscope works (itself requiring proof of the Conservation of Angular Momentum) Which means we're already in the domain of Newtonian mechanics, which came almost 80 years after Kepler's laws of planetary motion which gave us a clear understanding of the motion of a bunch of “stars” (yes, planets are not stars but they have the same kind of “star trails”). The really cool thing about star trails is that it's something really intuitive and easy to observe, and as such it makes a pretty convincing “proof” of earth rotation. Unlike the “proof” in this article, which will leave most people unimpressed (and which as I said earlier, uses a much more advanced physics theory than what's needed if you really want to prove earth rotation with star trails).
deleted 5y ago
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nyc111 5y ago

We know stars are distributed in various distances, this we know by observation. If not the earth but the stars rotate we must assume that billions of crystal spheres at different distances somehow rotate in exact coordination to trace the star trails that we observe. I don’t think there is such a huge “conspiracy” of crystal spheres to fool us.

codethief 5y ago
> We know stars are distributed in various distances, this we know by observation. How do we know? Establishing the cosmic distance ladder requires far more elaborate tools than the ones discussed here (Special and General Relativity, for instance) and the necessary measurements and observations also presume in one way or another that Earth is rotating. Even if you're only talking about stars in our immediate neighborhood for which a distance measurement merely needs the parallax effect (instead of SR or GR): In this case the parallax effects literally rests on the rotation of Earth and its orbit around the sun.
- nyc111 5y ago
  > the necessary measurements and observations also presume in one way or another that Earth is rotating. Yes, the lack of star parallaxes were the main argument offered by Tycho Brahe against a moving earth theory. When star parallaxes were observed the motion of earth was accepted. The way I understand it, to measure star parallaxes the earth must move. This is not an assumption, there is no circular reasoning. And we observe different parallaxes for different stars, meaning that stars are not all on the same distance from earth. I don't know if this is a trend like flat earthers to say that all stars are the same distance from the center of the universe? > In this case the parallax effects literally rests on the rotation of Earth and its orbit around the sun. So, this way you prove that the earth moves and stars have different parallaxes and are not all attached to a crystal sphere. I don't see a problem here.
  - sandworm101 5y ago
    Stars can still have parallaxes while bolted to the spheres. Maybe the spheres themselves wobble a little. Maybe the motion of the sun around the earth imparts a slight motion to closer spheres. The fixed stars are obviously on spheres far enough away that the sun doesn't shake them.
  - throw0101a 5y ago
    > Yes, the lack of star parallaxes were the main argument offered by Tycho Brahe against a moving earth theory. Much earlier than Brahe. Aristotle in De Caelo (Book II, part 14): > The earth, then, also, whether it move about the centre or as stationary at it, must necessarily move with two motions. But if this were so, there would have to be passings and turnings of the fixed stars. Yet no such thing is observed. The same stars always rise and set in the same parts of the earth. * http://classics.mit.edu/Aristotle/heavens.2.ii.html http://classics.mit.edu/Aristotle/heavens.2.ii.html * https://en.wikipedia.org/wiki/On_the_Heavens https://en.wikipedia.org/wiki/On_the_Heavens
  - codethief 5y ago
    > This is not an assumption, there is no circular reasoning. Of course it is an assumption. A star moving across the sky is not a proof by any means. > And we observe different parallaxes for different stars, meaning that stars are not all on the same distance from earth. No, we don't measure different parallaxes for different stars. We measure different trajectories for different stars across our night sky and then, using the assumption that Earth rotates and that it is on an orbit around the sun, we conclude that there must be a parallax effect involved in the observed trajectory of the star which we can then use to estimate its distance to us. > So, this way you prove that the earth moves and stars have different parallaxes and are not all attached to a crystal sphere. I don't see a problem here. To see that what you're referring to as "proof" is no proof at all, consider that Ptolemy's epicycles (i.e. the elaborate version of the crystal spheres) are just a Fourier series and can therefore be used to describe any periodic movement across the sky. (Without you having to know anything about whether Earth rotates or not.) For a very impressive example see https://m.youtube.com/watch?v=QVuU2YCwHjw https://m.youtube.com/watch?v=QVuU2YCwHjw .

nyc111 5y ago

“Stars have their own proper motions" is not an easy fact to prove. . .” No, proper motions are well known, https://www.britannica.com/science/proper-motion#:~:text=proper%20motion%2C%20in%20astronomy%2C%20the,distant%20background%20stars%20or%20galaxies https://www.britannica.com/science/proper-motion#:~:text=pro.... So we must further assume that a star attached to a crystal sphere will have a separate motion which also need to be explained.

IanCal 5y ago
It's well known that the earth rotates too though.
sandworm101 5y ago
>> a star attached to a crystal sphere will have a separate motion Two spheres. Proper motion can be explained completely if we allow each star to exist on its own crystal sphere. Layers of spheres could also extend great distances. Maybe the universe is vast, but it is all spheres. What does disprove spheres are collisions of objects having different proper motions.
- nyc111 5y ago
  > Two spheres. Proper motion can be explained completely if we allow each star to exist on its own crystal sphere. Wow! I can believe we are discussing in the age of Hubble space telecope and Webb etc. the existence of crystal spheres and how they can explain motions of stars. I don't believe crystal spheres exist but I respect your belief in them. To me they are an unnecessary and cumbursome explanation.
  - FredPret 5y ago
    Nobody believes in crystal spheres. The point is they are not so trivial to disprove.
  - sandworm101 5y ago
    As cumbersome as unobserved massive particles representing the majority of matter in the universe?

littlestymaar 5y ago

> This article is saying that if you can prove how a gyroscope works (itself requiring proof of the Conservation of Angular Momentum) Which means we're already in the domain of Newtonian mechanics, which came almost 80 years after Kepler's laws of planetary motion which gave us a clear understanding of the motion of a bunch of “stars” (yes, planets are not stars but they have the same kind of “star trails”). The really cool thing about star trails is that it's something really intuitive and easy to observe, and as such it makes a pretty convincing “proof” of earth rotation. Unlike the “proof” in this article, which will leave most people unimpressed (and which as I said earlier, uses a much more advanced physics theory than what's needed if you really want to prove earth rotation with star trails).

deleted 5y ago

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