Talk:Tychonic system
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[edit] "Brahe"
I was puzzled by the references to the scientist as "Tycho" rather than "Brahe," so it seems worth noting the reason for this (according to the Tycho_Brahe page, anyway). Supposedly this was the convention of the time in his native Scandia, and has become convention. --Stellmach 01:14, 16 July 2006 (UTC)
[edit] Stellar parallax
I removed the comment about how the Tychonic system has the "advantage" of not predicting stellar parallax. The distances to the stars were not known when Copernicus and Brahe were alive, so I don't understand how parallax could be a scientific issue at the time. If I'm mistaken about this and people did consider parallax to be an issue, please supply a citation for this and I'll shut up. --Shastra 18:43, 2 August 2006 (UTC)
- They didn't know the distance to the stars, no, but they did consider it to be a lot smaller than it actually is. They certainly knew that you got a null result from measuring stellar parallax—this is how Tycho decided that his "new star" in 1572 was not just a comet (he got a null result for the parallax measurement, and claimed that this was typical of something at the distance of stars—i.e. in the eighth sphere—and he had confirmed that stars show no parallax).[1]
- Here is a quote from Thoren's book on Tycho:
- By the 1570s however, there was a growing interest among younger men in the implications of the Copernican cosmology. The problem was that if the earth moved, there should be an annual parallax or shift in the apparent positions of the stars. If this annual parallax could not be detected, it would imply that the universe and the individual stars were so immense as to stagger the imagination. The same line of thought led to a reconsideration of the order and distances of the planets and even to speculation about the infinite size of the universe and a plurality of worlds. The appearance in 1572 of the new star also raised the possibility of a dynamic rather than static universe. ... The only empirical test [of the Copernican theory] lay in seeking astronomical parallax. Fortunately for the development of science, this test was single edged. It could prove the motion of the earth but not disprove it, as the failure to find the earth's motion reflected in an annual displacement of the stars could be explained away (and had to be, for three hundred years) by postulating stellar distances too remote to allow detection of the displacement. But the fact remained that the one astronomical check available provided negative evidence.[2]
- I don't know if it has to be labeled as an advantage (I understand it sound awkward since it is now known that this theory is incorrect, but in its time that was an advantage and the reason it could stick around as long as it did), of course. In any case I respect your desire for a citation. --Fastfission 19:28, 2 August 2006 (UTC)
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- OK, I stand corrected. Thanks for the reference. I still think this needs to be formulated in a way that makes the circumstances more clear (regarding the advantage part). If you want to revert again in the meanwhile, I won't interfere. --Shastra 19:49, 2 August 2006 (UTC)
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- I'll write it up in a more clear way in a little bit, to make it clear what aspects were and weren't as much of an issue in their time. --Fastfission 21:04, 2 August 2006 (UTC)
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[edit] Blunder on Bessell and Henderson
The current following last para obviously a blunder on Bessell and Henderson who discovered stellar parallax in the 1830s, not stellar aberration in early 18th.
"The discovery of stellar aberration in the early 18th century by Bessel, Henderson and James Bradley established that the Earth did in fact move around the Sun, after which Tycho's system fell out of use among scientists. In the modern era, the few who still subscribe to geocentrism use a Tychonic system with elliptical orbits."
Will correct --Logicus (talk) 19:07, 10 January 2008 (UTC)
