John McCreery wrote
Copernicus died in 1543. Galileo announced his observations of the
craters of the moon and the moons of Jupiter in 1609. As late as 1892,
we find the following in Oxford University Observatory Observations,
vol. 4, pp. 1-24 "History of Research in Stellar Parallax"
Tycho Brahe, Kepler, and Galileo, all occupied themselves with this
problem of Stellar Parallax, but the solution was hopeless; for the
former, on account of their preconception of the fixity of the
Earth, and even for the two latter, and after the adoption of the
Copernican system, on account of the comparative imperfection of the
telescope and the roughness of its micrometrical equipment. The word
comparative is here designedly used, for it is doubtful whether
even our modern instrumental advantages reach beyond the lower
limits of precision necessary to the determination of such
exceedingly minute quantities, as those concerned in the
investigation of the annual parallax of a star.
Google is a wonderful thing.
God wot. It pains me to see Tycho so easily dismissed by those Oxford swells. He was a hero of astronomy—the first to 'discover' a supernova, and to show that it was a celestial event, thereby demonstrating that the heavens were not unchanging, as they had been taken to be on the Aristotelian model; his careful observations of Mars provided Kepler with evidence that the planets moved in elliptical orbits. And much else.
As for his being unable to solve the stellar parallax problem because of his 'preconception of the fixity of the earth,' the reason he could not solve it was that although his instruments were among the best in the pre-telescope age, they were not precise enough to detect stars' parallax. This excerpt from
http://www.astro-tom.com/biographies/tycho_brahe.htmgives a more elegant explanation of the conclusion he drew from his failure. It had nothing to do with his preconceptions.
'He made the best measurements that had yet been made in the search for stellar parallax. Upon finding no parallax for the stars, he (correctly) concluded that either the earth was motionless at the center of the Universe, or the stars were so far away that their parallax was too small to measure.
'Not for the first time in human history, a great thinker formulated a pivotal question correctly, but then made the wrong choice of possible answers: Brahe did not believe that the stars could possibly be so far away and so concluded that the Earth was the center of the Universe and that Copernicus was wrong.'
Robert Paul, unable to see any stars tonight ------------------------------------------------------------------ To change your Lit-Ideas settings (subscribe/unsub, vacation on/off, digest on/off), visit www.andreas.com/faq-lit-ideas.html
