History of Heliocentrism

[Lorizael]

I'm conducting an informal survey of sorts.

Going back to ancient Greece or so, most astronomers subscribed to a geocentric model of the universe. Eventually, of course, that was superseded by a heliocentric model. When and why do you think this change occurred? That is, if you think a particular astronomer was responsible, what do you think that astronomer did (in terms of specific observations, say) to bring about the transition?

This isn't a quiz. I don't want people to look up answers or anything. I'm just trying to gauge what common knowledge is.

[BeBMan]

I vaguely remember there was at least one old Greek guy who developed a heliocentric worldview before BC? But without looking up I can't remember his name or when this became a more "common" thing, so ...

[Lorizael]

It's true that some Pythagoreans held to a heliocentric model, but Pythagoreans were also weird cultists who worshiped numbers.

[N35t0r]

Wasn't around this time that Galileo refined his telescope, and this provided better observations against geocentricism? (Among other things, Jupiter's Galilean moons which were discovered then, and orbited Jupiter)

[Ecthy]

In Western early modern tradition (ignoring some obscurity from ancient days), Copernicus challenged the geocentric position held by the church. Kepler and Galilei advanced knowledge about the shape of the planetary revolutions. Copernicus himself probably did improve upon some other people's works, including some old Greeks.

And noone ever held Earth to be flat-shaped, except Ben

[The Mad Monk]

From memory: Nicolus Copernicus published the theory sometime before Galileo, but didn't get in trouble with the church because he wasn't a troll. It didn't reach acceptance for some time, but certainly by the 1700s. The Greeks were aware that the Sun was pretty damn big and much bigger than the moon, because eclipses and math.

[Ben Kenobi]

When and why do you think this change occurred?

Kepler's use of Tycho's observations provided empirical observations of the mathematical relationships between the period and the radius of orbits of the planets within the solar system. These observations were well fitted to elliptical orbits with the sun at one focus.

[Buster Crabbe's Uncle]

Tycho Brae and his gold nose popped into my head when I read the OP, then Copernicus was mentioned -which had completely slipped my mind, d'oh- and Ben mentioned Tycho before I got down here to answer...

[N35t0r]

Wasn't Tycho's model a hybrid, with the moon and sun orbiting the earth and everything else orbiting the sun?

But yeah, Galileo's observations were based on Kelpler and Copernicus.

[Jon Miller]

The Copernicus Principle and associated Copernican Revolution is one of the key principles of modern science and western thought and a key foundation of the enlightenment. It was developed due to observations by Brahe and others that challenged the epicycle based model of the day. The central principle is that we do not live at some special location (like the center) of the universe.

We are still challenging and being challenged by the Principle today (for example, consider the ( weak and strong) Anthropic Principle and the various Multi-Universe frameworks considered).

JM

[Lorizael]

Wasn't around this time that Galileo refined his telescope, and this provided better observations against geocentricism? (Among other things, Jupiter's Galilean moons which were discovered then, and orbited Jupiter)

So the interesting thing is that the accepted cosmology of the day was a weird mishmash of Aristotelian physics, Ptolemaic geocentrism, and Christian theology. When Galileo (and others) first pointed telescopes upwards, they made a few significant discoveries that each put holes in different parts of this cosmological synthesis. The discovery of Jupiter's moons and that our moon had geological features (and later, that the Sun had sunspots) were points against Aristotelian physics, which demanded that (a) everything from the moon up had to be perfect and unchanging and (b) everything revolves around the Earth because the Earth is the center of the universe (which you can tell because the Earth is heavy and has "sunk" to the center).

The big mark against geocentrism itself was the observation of Venus' phases. The specific pattern of those phases was incompatible with Venus orbiting the Earth and could only be explained by Venus orbiting the Sun. That discovery caused most astronomers to shift to the Tychonic model N35t0r mentioned, which had the Sun, Moon, and stars orbiting the Earth and the planets orbiting the Sun.

One of the hits to contemporary Christian theology made early on was the discovery that there were way more stars out there than could be seen by the unaided eye. Some argued that if the universe were made just for us, what were all those invisible stars doing out there for thousands of years? This is more significant than it seems because a prevalent line of thought was that the purpose of the stars was to help us keep track of the seasons, so invisible stars didn't do us any good.

Galileo did not convince most other astronomers that heliocentrism was correct, and there were very good scientific reasons why those astronomers were not convinced. As others have said, opinion did not really begin to change until Kepler (who got his data from Brahe) put out his planetary tables, which made exquisite calculations based on an elliptical, heliocentric cosmology.

[Lorizael]

Nicolus Copernicus published the theory sometime before Galileo, but didn't get in trouble with the church because he wasn't a troll.

Galileo was totally a troll. He convinced his friend the pope to let him write a book fairly comparing heliocentrism and geocentrism with the goal of showing that Catholics (as opposed to Protestants) weren't fools but were educated and knew all about the latest astronomical stuff. But the actual book was not even remotely balanced and painted (his friend!) the pope as a moron.

[Aeson]

I learned about heliocentrism from astrology.

[Bereta_Eder]

I bet those are more accurate than merril lynch and the like

[The Mad Monk]

Galileo was totally a troll. He convinced his friend the pope to let him write a book fairly comparing heliocentrism and geocentrism with the goal of showing that Catholics (as opposed to Protestants) weren't fools but were educated and knew all about the latest astronomical stuff. But the actual book was not even remotely balanced and painted (his friend!) the pope as a moron.

Yes, exactly. It mildly annoys me how that is left out of the popular version of the story.