We finally got parallax in 1806 by Giuseppi Calandrelli in α-Lyrae.
Stellar parallax was considered since at least Aristotle, as he mentions in his On the Heavens (II.14), and since it is not observed then it is reasonable to conclude that there is no motion (it took several thousand years to develop instruments to actually measure it).
Daniel Whitten's "Matters of Faith and Morals Ex Suppositione" is an interesting read.
I'd think that the Earth rotating would be obvious much, much sooner, since that's far less work than the entire universe orbiting around the Earth every day, while also having individual objects orbiting on their own monthly, annual and other cycles. And spinning tops are common toys.
Keep in mind that there was nothing indicating that the sun and the stars were of the same nature, or that they were so far away. When you think about it, all stars appear equally distant to the naked eye, so the idea that stars were fiery stones dispersed on a vast celestial sphere was absolutely plausible. This solid, physical sphere was the thing rotating.
Also people had little understanding of the scale of things. There is nothing indicating that the moon is smaller than earth or that the sun is much, much bigger than earth, and both appear equally large in the sky...
> Also people had little understanding of the scale of things. There is nothing indicating that the moon is smaller than earth or that the sun is much, much bigger than earth, and both appear equally large in the sky...
The Ancient Greeks were actually quite clever about trying to calculate things:
> I'd think that the Earth rotating would be obvious much, much sooner […]
How exactly could you tell the difference between one moving reference and another? Einstein eventually showed us that it is not possible.
As this US Navy video shows, having the Earth stand still and having the 'celestial sphere' move actually makes celestial navigation using a sextant possible / mathematically easy:
Einstein did not show that. The principal you are referring to is, ironically, Galilean relativity, and attributable to Galileo. Einstein's contribution was combining the principle of relativity with a constant speed of light.
Additionally, under both systems, relativity only applies to intertial reference frames. Rotating reference frames are detectable.
You can detect Earth's rotation without any external observations using a pendulum. Although such an experiment would not be done until Léon Foucault about 2 centuries after Galileo.
You can tell the difference between rotating and not, because a rotating reference frame is not inertial. In fact, the geocentrists knew this, because one of the longest-standing objections to the idea that the earth rotated was that you would expect a falling object to be displaced from the apparent vertical due to the rotation, these experiments were done, and the displacement was not observed (it turns out, because the effect was so small, but no-one would have the mathematical tools to work this out until Newton).
It is easy to treat Galileo as fighting the obscurantist church of the 15th century, but as the article explains briefly:
> provocatively voiced the pope’s own arguments through an obtuse Aristotelian called Simplicio
... Galileo's ordeal with the inquisition was mostly due to him making fun of the pope (probably not a good idea). The truth is that until Kepler introduced elliptical orbits and variable orbital speeds, the Copernican heliocentric model still needed epicycles and was not much better than the ptolemaic model.
And the church didn't even care _that_ much. Copernicus himself was a priest and, while he himself was wary of publishing it and framed it as a way to do astronomical calculations without any kind of philosophical implication, in the end it circulated without much fuss.
This of course should not diminish his contributions to the scientific method and his other contribution to astronomical observations (mostly the satellites of Jupiter and the rings of Saturn, though his instrument wasn't good enough to recognize them as rings).
> Galileo's ordeal with the inquisition was mostly due to him making fun of the pope (probably not a good idea).
And at least one history I read on the subject questions whether Galileo was even intending to make fun of the Pope. My memory of the basic story that book told:
- The Pope encouraged Galileo to publish a book with his new theories, but just told him to add a theological "escape hatch" (provided by the Pope himself) to make sure he wasn't viewed as heretical
- The book is a dialogue between three people, one of whom, "Simplicio", is kind of stupid and backwards the whole book, but in the last chapter says effectively, "Actually I've just been pretending this whole time to be foolish; but actually I"m wise, and let me tell you why." He then gives the Pope's argument and the book ends -- giving the Pope the last word, as it were.
- At the time no books can be printed unless they're officially approved by the Church as being non-heretical. The book was reviewed, and approved, by two different Papal censors in two different cities. It was only sometime later that the Pope became offended by his words being placed in Simplicio's mouth; in what the author I read thought was almost certainly a misunderstanding.
As the author said, Galileo was encouraged to write the book; was told some theology to put into it; he did so. The book was submitted for review and approved twice. What more could Galileo have done?
If I could read Renaissance Italian I'd go back and read it and judge for myself. Anyone here read it that can weigh in on the theory that Galileo never meant to offend the Pope?
You need not make any excuses; they are superfluous, and especially so to me, who, being accustomed to public debates, have heard disputants countless times not merely grow angry and get excited at each other, but even break out into insulting speech and sometimes come very close to blows.
As to the discourses we have held, and especially this last one concerning the reasons for the ebbing and flowing of the ocean, I am really not entirely convinced; but from such feeble ideas of the matter as I have formed, I admit that your thoughts seem to me more ingenious than many others I have heard. I do not therefore consider them true and conclusive; indeed, keeping always before my mind's eye a most solid doctrine that I once heard from a most eminent and learned person, and before which one must fall silent, I know that if asked whether God in His infinite power and wisdom could have conferred upon the watery element its observed reciprocating motion using some other means than moving its containing vessels, both of you would reply that He could have, and that He would have known how to do this in many ways which are unthinkable to our minds. From this I forthwith conclude that, this being so, it would be excessive boldness for anyone to limit and restrict the Divine power and wisdom to some particular fancy of his own.
[ends]
That doesn't seem like it's quite the same as what you're saying you read. Simplicio ends up professing a sort of pious agnosticism about what Galileo is talking about. I don't get any particular sense from this that we're meant to think "oh, hey, Simplicio is much smarter than we were giving him credit for being".
(I do not know enough about any pope's astronomical opinions to have a useful opinion on how closely Simplicio's professed positions match those of the pope, or how likely it is that Galileo was and/or seemed to be making fun of the pope. My highly inexpert impression was that Simplicio wasn't modelled on the pope specifically but on other people with whom Galileo had more of a grudge.)
> I do not therefore consider them true and conclusive; indeed, keeping always before my mind's eye a most solid doctrine that I once heard from a most eminent and learned person, and before which one must fall silent,
Assuming that the following really is the "theological angle" suggested by the Pope, it's literally saying that the Pope is a most eminent and learned person, and that the argument he's made is "solid doctrine" and an unassailable argument. And Simplicio isn't coming up with the argument himself; he's saying he's heard it from this other eminent and learned person. All that's perfectly consistent with a good-faith attempt to flatter the Pope's wisdom and influence, and accommodate his request regarding the theological "escape hatch".
Unfortunately, it's also fairly open to being construed as being a sarcastic insult... or even an attempt at a sort of "dog whistle", where "devout" people take it as face value, but people "in the know" take it as being sarcastic.
EDIT: And, seriously:
> I know that if asked whether God in His infinite power and wisdom could have conferred upon the watery element its observed reciprocating motion using some other means than moving its containing vessels... From this I forthwith conclude that, this being so, it would be excessive boldness for anyone to limit and restrict the Divine power and wisdom to some particular fancy of his own.
It's not saying "God could just magic things to make the water appear to move like this"; it's "There are lots of other possible reasons why the water might appear to move like that".
It sounds to me like a description of necessary scientific humility. We have these observations, this one theory is consistent with them, but there lots of other possibilities, so we should keep an open mind and not be too insistent on one particular theory.
It turns out the trial of Galileo was based on a clerical error. They were going through his file and found a document that seemed to say he had pled guilty to a heresy several years earlier, and he was bound by a consent decree that prevented him from teaching heliocentrism. They hauled him to court and accused him of violating the consent decree. Galileo promptly pulled out paperwork showing that he had been cleared in that investigation, he WAS permitted to teach heliocentrism (as a hypothesis), and the judges were looking at an unsigned draft document that never went into effect. It seems to be the case that he never would have been tried if that bogus document hadn't been left in his file.
Galileo also couldn't explain the lack of an observed parallax effect between opposite seasons given the ideas about optics at the time.
When Kepler's model arrived, it was so much better at predicting the positions of all planets except Mercury than any previous model that it was clearly superior. Galileo's was bad at predicting and just contradicted the accepted observations of the day.
IMO Galileo should be better remembered for objects of different masses falling at the same rate and the original idea that all motion is relative (when observing from an internal frame).
> Galileo also couldn't explain the lack of an observed parallax effect between opposite seasons given the ideas about optics at the time.
That's not entirely correct. The lack of parallax was explained by the stars being far away; the problem with that explanation is that Brahe had measured the apparent stellar diameter of stars, which implied that for the stars to be as big as they appear to be to us, they would have to be far, far larger... which violates the underlying Copernican principle that the sun is but a normal star.
The Copernican model was heliocentric, surely? It placed the sun motionless at the centre of the universe. That makes the sun anything but a normal star.
The copernican principle is separate from the model. Basically it says that our position in the universe is random - we don't exist at the center of the universe.
"Hermann Bondi named the principle after Copernicus in the mid-20th century, although the principle itself dates back to the 16th-17th century paradigm shift away from the Ptolemaic system, which placed Earth at the center of the universe. Copernicus proposed that the motion of the planets could be explained by reference to an assumption that the Sun is centrally located and stationary in contrast to the geocentrism. "
"Hermann Bondi named the principle after Copernicus in the mid-20th century, although the principle itself dates back to the 16th-17th century paradigm shift away from the Ptolemaic system, which placed Earth at the center of the universe... Copernicus himself was mainly motivated by technical dissatisfaction with the earlier system and not by support for any mediocrity principle."
Copernicus' solar-system model is entirely separable from any assumptions about star size distribution, and the latter was apparently not a concern of his (nor do I recall seeing anything to the contrary elsewhere.)
On account of this separability, the mediocrity principle cannot be used to eliminate heliocentric models of the solar system from consideration, at least unless there's good evidence for it.
Nevertheless, the presumed huge size of the stars was seen as more or less of a problem (depending on which way one leaned on the heliocentricity issue), but it turned out that the apparent size of the stars was merely an artifact created by diffraction (the Airy disk) [1], making it possible to hold both that the sun is well within the range of stellar sizes and that other stars are far enough away that their parallax is difficult to observe.
That sort of makes sense but the comment I replied to was still mistaken in linking the 20th century "Copernican principle" to debates in the time of Galileo.
IMO calling something so greatly at odds with Copernicus's model the "Copernican principle" is misleading (if not outright nonsensical) and explains why the commentor I corrected confused the two. What a good idea to name something completely at odds with Copernicus's view of the universe after him.
Its like "Gell-Mann amnesia" but without the humour or self awareness.
They cared enough to put heliocentric books on the index of forbidded books for centuries. Gallileo might have offended the Pope, but the works of Copernicus was also forbidden.
There's a weird amount of apologism for the actions of the Church towards Galileo. "Oh but he insulted an authority" - like, that doesn't make it better.
I mean they also just straight up incinerated a man for daring to suggest aliens might exist[1].
Organized religion is, and remains, an authoritarian system of oppression.
Did you know that in quite some countries you are officially not allowed to mock foreign leaders either? I mean it’s usually not enforced, but it’s definitely part of the law
Their goal was to limit what support Galileo could gain for his works in public discurse. It most likely helped with that. It also did not stop scientists from improving on the copernican model without incurring the wrath of the church, they just used earth as point of reference to make the model geocentric.
> Galileo Galilei’s muttered protest symbolises the triumph of scientific rationality over blinkered, obstructive theology. In the face of all the facts – or so runs the mythology – Pope Urban VIII had refused to accept that the earth is in perpetual motion around the sun. He condemned the heretical astronomer to the relatively mild punishment of house arrest,
Weaselly writing! What is claimed as "myth" here? That theology was obstructive? Did the Pope put his thumb on the scales or not? Did the Pope sentence Galileo to house arrest?
> the pope won that round of the battle by sentencing him to nine years of house arrest.
The main myth is that: Galileo was obviously right given the evidence at the time, and that the Catholic Church pursued him entirely because they were unwilling to change their view. The evidence instead suggests that the Catholic Church was primarily concerned (oppressively so) about explicit interpretation of scripture, but not so much (as an institution) concerned about matters of speculation about models of the solar system, especially when they were specifically couched as such, and they were also quite willing to adjust their interpretations of scripture if those interpretations were actually falsified by evidence. The problem was the Galileo a) didn't have that evidence (and the evidence he tried to present was wrong: the book that got him in trouble focused on an argument from the tides where he assumed the tides go up and down once a day! He had some other better ideas but the experiments/observations didn't work, sometimes due to sheer bad luck), b) was advocating for a model that absent that evidence was mathematically equivilent to a geocentric model (there were many: only the simplest were eliminated by the new observations of phases of Venus) but more complex (Kepler had the right idea but Gallileo was insistent on the epicycles of circles), and c) made a lot of friends into enemies by generally being an arrogant credit-hoarder, as well as having more unreasonable enemies.
The events that lead up to the house arrest were quiet chaotic as well: an almost comedy of errors meant that Gallileo's book never got a full review in context before publishing and so the implied insult of the Pope was published with Gallileo seemingly believing it had been approved beforehand (seemingly Gallileo had understood the Pope's attitude to be a "just make sure you put a small fig leaf on it until we change our official position" instead of "You don't actually have enough evidence to disprove this other theory, but it's worth writing something up considering both"). The trial also involved a bunch of skullduggery where various documents were fabricated (by parties unknown, though some would have needed to be inside the church) to paint Galileo as if he had directly opposed the church on matters of scripture, which was what ultimately got him in trouble.
So, was the Catholic church extremely overbearing and oppressive in regulating the speech and writings of others? Yes, for sure. But on a quite limited scope: they cared relatively little for scientific speculation. Could Galileo have basically published the same information and not gotten into trouble? Also yes. It took a dedicated conspiracy to try to paint him as attacking the church and him pissing off almost all his friends (including one quite powerful one) for him to get punished.
So, the full story makes the church and pope appear a little more reasonable. It's still unreasonable that they were in the position of "Falsify the current consensus or keep your statements couched in speculative terms", but it's far from "No, shut up with your obvious truth". Similarly, Galileo looks a lot less reasonable: basically insisting he's correct when his own proposal is unwieldy and still only correct in a few more details than the consensus, and it appears mostly by accident because he was unable to actually collect convincing evidence for those details (it's notable that he also didn't really convince many others either. Eventually Kepler's model took over due to mathematical convenience and then more precise measurements provided the evidence Galileo lacked). And there's a whole third part where some even more unreasonable people are trying to take Galileo down for a much smaller slight, and eventially their efforts do contribute to that.
Feyerabend has an interesting account of this in “Against Method”. One thing I also found very interesting in his telling is the role of the telescope in revolutionizing naval warfare. Galileo in part was motivated, and supported by, a sort of proto-military-industrial complex.
Galileo was thought to be in the wrong not necessarily for scientific views, but for implied theological arguments based on those views.
For example, scientifically and theologically I thought geocentrism was the prevailing view at that time among scientists (God created the earth as a kind of "moral center" of the universe of God's Creation?); today acentrism (universe has no center) seems to be a prevailing scientific view. So by this logic, Galileo was wrong by modern scientific standards, and theologically some still argue for a kind of geocentrism or other such views (such as "galileowaswrong.com" or other such sites) against Galileo's theological views.
Hence Galileo was rightly criticized for lacking religious caution; his rebellious attitude against religion (again, not necessarily for supporting a speculative scientific view) indeed has caused centuries of harm, pitting science against religion, whereas true science can never contradict religious truth.
Not all that much: they both suffered from assuming that everything was perfect circles, so they needed nested epicycles to match observations. Galileo's model actually needed more than Riccoli's (one reason why it was not so popular). They both predicted the observed motions of planets equally well, the two main differences were the nature and position of the stars and whether the earth or sun were at the center, Those two are related: if the earth is at the center, then you can put the stars more or less wheverever you want in the model and things don't change. If the sun is at the center, you need to put the stars very far away because the observations of the day didn't show any parallax of the stars due to the earth's rotation around the sun. This was unpopular because both telescopic and naked eye observations of the stars appears to show them as a disk (about the same size as Saturn) instead of a point, which would mean stars would need to be even larger than the solar system to match observations. It was only centuries later that this was shown to be an optical illusion. The other objection was the Galilean model also requires the earth to rotate around its own axis, which was also an unpopular idea for a variety of reasons, chiefly it creates a bunch of questions which need a good understanding of ideas like mass, velocity, and momentum to answer, and it wasn't until Newton that all that was really put into a good framework. The most robust argument was related to coriolis effects: if the earth is rotating, you would expect that a dropped object would not fall straight down, but instead land slightly west of the point where you dropped it. People had tried this experiment and did not see the effect (mostly because it's really small). So Galileo more or less could not really produce an experiment which his model could explain and Riccioli's model could not, and for the areas where it differed he could only really shrug his shoulders and say 'maybe the effect is too small to measure'.
(Not for lack of trying: apart from the dropping weights experiments done by others, Galileo also attempted to measure parallax of two stars that are close together in the sky. Unfortunately he picked a binary system where the stars are also close together in distance, and so he didn't see anything. He also had an argument based on the tide, which was apparently what originally convinced him of the idea. This argument was unfortunately obviously wrong in some important ways: he thought that the tides were due to the earth spinning and 'pulling along' the oceans, and his model worked out that the tides would rise and fall once a day, in contradiction to the experience of every sailor at the time)
1. Heraclidean. Geo-heliocentric. Mercury and Venus circle the Sun; everything else circles the Earth.
2. Ptolemaic. Geocentric, stationary Earth.
3. Copernican. Heliocentric, pure circles with lots of epicycles.
4. Gilbertian. Geocentric, rotating Earth. (proposed by William Gilbert in De magnete)
5. Tychonic. Geo-heliocentric. Sun and Moon circle the Earth; everything else circles the Sun.
6. Ursine. Tychonic, with rotating Earth.
7. Keplerian. Heliocentric, with elliptical orbits.
See:
* https://tofspot.blogspot.com/2013/08/the-great-ptolemaic-sma...
* ToC: https://tofspot.blogspot.com/2013/10/the-great-ptolemaic-sma...
* PDF: https://faculty.fiu.edu/~blissl/Flynngs.pdf
By the mid-/late-1600s people leaned toward Kepler, mostly because the math was easiest.
With regards to evidence for the Earth's motion, the first inkling was in 1728 with stellar aberration with in γ-Draconis:
* https://en.wikipedia.org/wiki/Aberration_(astronomy)#Discove...
The first for the rotation of the Earth (around an axis) was in 1791 by Guglielmini:
* https://en.wikipedia.org/wiki/Giovanni_Battista_Guglielmini
We finally got parallax in 1806 by Giuseppi Calandrelli in α-Lyrae.
Stellar parallax was considered since at least Aristotle, as he mentions in his On the Heavens (II.14), and since it is not observed then it is reasonable to conclude that there is no motion (it took several thousand years to develop instruments to actually measure it).
Daniel Whitten's "Matters of Faith and Morals Ex Suppositione" is an interesting read.