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Maybe we couldn't distinguish "the earth goes around the sun" from "the sun goes around the earth" until 1806, but we could tell that the other planets have the

Maybe we couldn't distinguish "the earth goes around the sun" from "the sun goes around the earth" until 1806, but we could tell that the other planets have the sun, rather than the earth, as their primary much earlier than that. Isn't that the most important difference between the systems?

namarie 9y ago
No, because there was a system (the Tychonic system IIRC) where the sun orbits the earth and the planets orbit the sun. It seems to have been popular at the time also.
throw1002a 9y ago
@namarie got it right. Per Part 3 in the series: In the second episode, we saw a slew of new telescopic discoveries during 1610-1611; viz., the mountains on the moon, the Medicean stars, and (more decisively) the phases of Venus. Now the first two do not demonstrate geomobility, not do they undermine geostationarity. The first indicates that the moon is not incorruptible. But this is agreed to by theology, and it undermines only Aristotelian physics. The second indicates that some heavenly bodies -- Cosmo, Franco, Carlo, and Lonzo -- circle Jupiter and not the Earth. This bothers Aristotelian physicists, but not Tychonic astronomers. Only the phases of Venus KOs Old Man Ptolemy. But eliminating Ptolemy does not prove Copernicus any more than eliminating Darwin would prove ID. There may be [and were!] other alternatives. When Ptolemy was ptossed, astronomers flocked... to the Tychonic and Ursine systems -- because none of the telescopic observations have so far established the motions of the Earth. * http://tofspot.blogspot.com/2013/09/the-great-ptolemaic-smackdown-great.html http://tofspot.blogspot.com/2013/09/the-great-ptolemaic-smac... In Part 2 Flynn outlines the seven major models in play: * Heraclidean. Geo-heliocentric. Mercury and Venus circle the Sun; everything else circles the Earth. * Ptolemaic. Geocentric, stationary Earth. * Copernican. Heliocentric, pure circles with lots of epicycles. * Gilbertian. Geocentric, rotating Earth. (proposed by William Gilbert in De magnete) * Tychonic. Geo-heliocentric. Sun and Moon circle the Earth; everything else circles the Sun. * Ursine. Tychonic, with rotating Earth. * Keplerian. Heliocentric, with elliptical orbits. * http://tofspot.blogspot.com/2013/08/the-great-ptolemaic-smackdown-down-for.html http://tofspot.blogspot.com/2013/08/the-great-ptolemaic-smac...

namarie 9y ago

No, because there was a system (the Tychonic system IIRC) where the sun orbits the earth and the planets orbit the sun. It seems to have been popular at the time also.

throw1002a 9y ago

@namarie got it right. Per Part 3 in the series: In the second episode, we saw a slew of new telescopic discoveries during 1610-1611; viz., the mountains on the moon, the Medicean stars, and (more decisively) the phases of Venus. Now the first two do not demonstrate geomobility, not do they undermine geostationarity. The first indicates that the moon is not incorruptible. But this is agreed to by theology, and it undermines only Aristotelian physics. The second indicates that some heavenly bodies -- Cosmo, Franco, Carlo, and Lonzo -- circle Jupiter and not the Earth. This bothers Aristotelian physicists, but not Tychonic astronomers. Only the phases of Venus KOs Old Man Ptolemy. But eliminating Ptolemy does not prove Copernicus any more than eliminating Darwin would prove ID. There may be [and were!] other alternatives. When Ptolemy was ptossed, astronomers flocked... to the Tychonic and Ursine systems -- because none of the telescopic observations have so far established the motions of the Earth. * http://tofspot.blogspot.com/2013/09/the-great-ptolemaic-smackdown-great.html http://tofspot.blogspot.com/2013/09/the-great-ptolemaic-smac... In Part 2 Flynn outlines the seven major models in play: * Heraclidean. Geo-heliocentric. Mercury and Venus circle the Sun; everything else circles the Earth. * Ptolemaic. Geocentric, stationary Earth. * Copernican. Heliocentric, pure circles with lots of epicycles. * Gilbertian. Geocentric, rotating Earth. (proposed by William Gilbert in De magnete) * Tychonic. Geo-heliocentric. Sun and Moon circle the Earth; everything else circles the Sun. * Ursine. Tychonic, with rotating Earth. * Keplerian. Heliocentric, with elliptical orbits. * http://tofspot.blogspot.com/2013/08/the-great-ptolemaic-smackdown-down-for.html http://tofspot.blogspot.com/2013/08/the-great-ptolemaic-smac...