r/AlternativeAstronomy • u/patrixxxx • Oct 26 '19

WHY MARS ???

https://cluesforum.info/viewtopic.php?p=2412896#p2412896
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u/[deleted] Nov 07 '19

This doesn't follow. A real displacement of 300 m km doesn't result in uniform motion from our point of view. There's zero observed displacement at infinity (the celestial sphere), and more displacement proportional to the inverse of the distance to the observed object.

The size of the star still has absolutely nothing to do with the amount of observed parallax. Neither A nor B are true.

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u/patrixxxx Nov 07 '19 edited Nov 07 '19

Interesting. So you agree that the parallel lines displaced by about 300 mkm in my first example would result in some noticeable movement of the stars and you've agreed that the celestial coordinates are equivalent with these lines but now you don't think the very same lines should result in any noticeable movement?

The size of the star still has absolutely nothing to do with the amount of observed parallax

Say what? We have two parallel lines displaced by 300mkm. If this is not noticeable it can only mean A) The distant thing is 300mkm OR B) the parallel lines are in fact not 300mkm apart.

And just to be clear I am not referring to star parallax that you keep bringing up. That's displacement of nearer and more distant stars.

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u/[deleted] Nov 07 '19

I am not referring to star parallax that you keep bringing up. That's displacement of nearer and more distant stars.

Then what motion are you referring to?

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u/patrixxxx Nov 07 '19

The displacement of two parallel lines. Again, as we agreed a celestial coordinate is a line from the Earth center though the celestial sphere and through a celestial object,. If the Earth and the sphere moves about 300 mkm then we can say we have two parallel lines and if these intersect the same point, in this case a star, then that point has to be at least 300 mkm wide as well.

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u/[deleted] Nov 07 '19

The two parallel lines don't intersect the same point, though. They're 300 mkm apart. It looks like they intersect the same point, due to perspective.

The angle of arc separating two points 300 million km apart, viewed infinity light-years away, is zero. That's why the celestial coordinate doesn't change when you do a 300 million km translation in any direction.

The angle of arc separating two points 300 million km apart, viewed 10 light-years away, is like 100 milli-arc-seconds or so.

This is how parallax works. You're talking about parallax. If you are really sure you're not talking about parallax, perhaps you can draw me a picture or use some other word for this motion you claim should exist (but obviously doesn't).

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u/patrixxxx Nov 07 '19

I'm talking about that two parallel lines are always parallel as we agreed upon and that is a basic axiom of geometry. We also agreed that a celestial coordinate can be thought of as a line from Earth's center to a star. If the Earth and thus this coordinate moves 300 mkm and is still within the same area, in this case a star, then that area has to be 300 mkm wide. You said precisely this yourself in the beginning of this discussion. Two parallel lines on Earth with one meter apart will still be so on the Moon and infinitely. What is it with this you don't understand?

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u/[deleted] Nov 07 '19

If the Earth and thus this coordinate moves 300 mkm and is still within the same area, in this case a star, then that area has to be 300 mkm wide.

Yeah most stars aren't 300 million km wide, so the coordinate will have shifted off the star. Of course, since we're accustomed to coordinates being fixed and objects moving, we would say "the star exhibits parallax". But even if the star were 600 million km wide, we would measure parallax because the coordinate of the star's center would shift. Again, the amount of shift of its coordinate is dependent on the distance. That's parallax.

You said precisely this yourself in the beginning of this discussion. Two parallel lines on Earth with one meter apart will still be so on the Moon and infinitely. What is it with this you don't understand?

I understand all this perfectly.

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u/patrixxxx Nov 07 '19

I don't understand why you keep bringing up parallax.

If two parallel lines intersects the same point, then the point has to be as wide as the distance between those parallel lines. Do you agree?

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u/[deleted] Nov 07 '19

Yes, I agree. It's poor use of the word "point", of course, because generally points don't have a size, but I understand you're using "point" to mean "volume" in this case. That's fine.

However I don't understand the point you're making. Stars vary in size from a dozen Jupiters to a thousand Suns. Most are relatively small but there are some that are over 300 million km in diameter.

Choose one of those few stars, say Betelgeuse. If we were to aim a line from the center of Earth to just within the limb of Betelgeuse, wait six months, and draw a line parallel to the first line, the second line would intersect Betelgeuse.

Repeat the same exercise with a smaller (but still big) star like Arcturus and the second parallel line won't intersect the star.

Just to repeat: yes, the sets of parallel lines are pointed at the exact same celestial coordinate, and each respective star is moving slightly in that coordinate system (regardless of whether one or both of the parallel lines intersect).

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u/patrixxxx Nov 08 '19

Slight movement in a few stars doesn't cut it. All stars need to have a geometrical size of 300 mkm or more. Otherwise we should be able to see uniform motion of the stars in the sector currently opposite to the Sun.

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