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Researcher discovers another astronomy book written by Galileo Galilei (medievalists.net)
111 points by benbreen on Oct 13, 2022 | hide | past | favorite | 34 comments



I hoped it would be a completely new piece of work but what they actually found out is that an already known book was authored by Galileo under a pseudonym, which is a tad less exciting


Obligatory Podcast on this : https://podcasts.apple.com/gb/podcast/subject-to-change/id14...

"Subject to change" is a surprisingly great podcast and this is a pretty good episode.


"E pur si muove"

The biggest fuck you in history. I love Galileo.


Probably apocryphal.

Also the priests knew he was right.

He just pissed off the Pope and was punished for that, not for any astronomical ideas.

That was just the excuse.


It was a little more complicated as to whether the priests (and other astronomers) knew he was right.

Heliocentrism made a specific prediction of parallax --- namely that the stars would move back and forth over the course of a year. But this wasn't observed which is one of the main reasons that many astronomers remained skeptical of the idea. Tycho Brahe proposed an alternative model that adopted many of the advantages of heliocentrism but didn't have the parallax problem. In his theory all the planets revolved around the Sun, but the Sun revolved around the Earth.

Of course it turned out that the stars were much, much further away than anyone expected, so the parallax effect was too small to be seen until the 19th century.

But your broader point is correct, Galileo's troubles were brought about more due to his political indiscretions than his astronomy per se.


Another point, discussed in Arthur Koestler's The Sleepwalkers (I'm going from memory, so there may be slight errors), is that the Copernican model was pretty ugly:

1. It actually required more epicycles than the Ptolemaic model.

2. It didn't even have the other planets orbit the Sun! Rather, they orbited the center of the Earth's orbit (???).

Kepler's laws fixed all of this, but Galileo ignored all of Kepler's correspondence, except for one time when he found it profitable to use him: He had made claims about the Jovian moons based on observations through his telescope, but he refused to let other astronomers borrow that instrument so they could reproduce his observations. Kepler wrote to Galileo offering to defend him, and Galileo accepted. Then later, after Kepler had already publicly defended him and himself requested access to the telescope to verify the observations, he was ignored, as per all other times Kepler wrote him before and after.


Well, both things are wrong, planets do not orbit the sun or the center of earth's orbit, but the center of solar system, which is actually outside the sun.


It's true that due to the large mass of Jupiter, the barycenter of the solar system lies outside the surface of the sun.

However, the barycenter of any sun/planet 2-body system besides Jupiter lies within the sun's surface, so I'm quite comfortable with the claim that at the very least most planets do orbit the sun...


> Of course it turned out that the stars were much, much further away than anyone expected, so the parallax effect was too small to be seen until the 19th century.

How do we know how far away the stars are? (serious question)


This very parallax effect. We know how far the Sun is from the Earth, and the Earth has moved twice this distance from January 1 to July 1. This in turn allows us to extrapolate distance to some of the nearest stars by their apparent motion relative to the other, "fixed" stars.

https://en.wikipedia.org/wiki/Cosmic_distance_ladder

https://www.youtube.com/watch?v=7ne0GArfeMs


OK but then how do we know how far the sun is from the earth? Is it like "bounce a signal off it and count time of flight?"

(Another serious question.)


> The first rigorous and accurate scientific measurement of the Earth-Sun distance was made by Cassini in 1672 by parallax measurements of Mars. He and another astronomer observed Mars from two places simultaneously. A century later, a series of observations of transits of Venus provided an even better estimate.

http://curious.astro.cornell.edu/about-us/41-our-solar-syste...


We can't bounce signals off the sun, but we can do "interplanetary radar" bouncing signals off at least the nearby planets.

Knowing those distances, the distance to the sun becomes a trigonometry problem.


The video of Terence Tao I linked addresses that and many other questions about climbing the cosmic distance ladder.


I read this book, "Measuring The Cosmos", a few years ago, and it talks about the various ways we use to establish distances to such far objects. The book describes how we grew our "measuring tape" so to speak. We started with learning accurate distances to things closer, the distance from the Sun to Earth, an AU, being one of those. That's useful for local solar system distances, but the numbers become too big for human consumption when measuring further objects. Light years became the next rung on the ladder. Parsecs next, etc.

Now, we use certain types of stars like pulsars that have known brightness for the particular frequencies. Once we find a new pulsar that matches, we can compare how bright it is to others of the same type. If it is brighter, it is closer. If it is dimmer, it is further away. I'm way way oversimplifying it, but hopefully it gets the concept across.

https://www.amazon.com/Measuring-Cosmos-Scientists-Discovere...


The Greeks wrote in jest they hope that no one climbs to the top of Olympus, they would revolt upon finding there are no gods there.

To an extent those in the upper echelons of human society have always known the magical stories were bogus. But when the flock is dumber than Humperdoo himself, Humperdoo will do.


In my opinion, that would make things even worse:

The sentencing clearly states that the earth revolving around the sun "is a proposition absurd and false in philosophy, and formerly heretical", and by that time, Copernicus's De revolutionibus orbium coelestium had already been placed on the Index of Prohibited Books.

Are you saying the church actually knew Galileo was right, and did this anyway?


"Are you saying the church actually knew Galileo was right, and did this anyway? "

Not OP, but from what I know about the whole topic:

Not the church in its whole, but very likely the persons involved with the case and likely the pope knew.

In the way of, "technically he might be right, but those technical details are attacking the philosophy and very foundations of our church, which already is under heavy attack from all sides"

So you likeley have pure power motivation, but for "true believers" it was more, basically attacking the foundations of the one and only true church (this is what "catholic" actually means). So even if what Galilei said sounds true and logical, it cannot be true as it would question the truth of the believe, which is not to be questioned. Therefore the logic must be wrong.


They knew he probably wasn't wrong and didn't give a shit about it.

All they wanted was a way to punish him and going so clearly against "common sense" and orthodoxy was perfect and they used that.


>He just pissed off the Pope and was punished for that, not for any astronomical ideas.

It all comes down to politics and power structures in the end.


This can't be stressed enough.

He most certainly was not punished for any ideas, apart from making fun of the Pope and pissing off other people with power.


It's like social media. Europe was the Pope's subreddit. Don't piss off the moderator. It ain't rational but it's true.


It's even more like that than you might suspect; the old moderator stepped down (died) and the new one was a friend of Galileo, so he ignored warnings to not shitpost too much, and ate a very moderate "ban".


How did he piss off the pope?


Galileo had spoken of these ideas with the pope (who was a friend) previously and the pope was somewhat amenable to them, but still preferred geocentrism. The pope thought that Galileo should write up his ideas about heliocentrism, but asked that he include the arguments in favor of geocentrism as well. Galileo then wrote his work as a conversation consisting of two intelligent men, one who favors heliocentrism and a neutral arbiter, along with a slow-witted character appropriately named "Simplicio," who gives ridiculous arguments in favor of geocentrism. It was no mystery that Simplicio was a stand-in for the pope.


Thanks for your enlightening comment. This seems to be a well-written article that goes more into depth: https://thonyc.wordpress.com/2014/05/29/galileo-the-church-a...


It's quite interesting to think that this problem persists today - with the modern popes of the modern religions of course.


And it won't ever go away with social apes.


I really can't blame the guy. Imagine the evolution vs creationism "debates" of the 21st century and the creationists asking for "the other view" to be represented in public schools when we know for a fact that life and speciation didn't just appear ex-nihilo.

Honestly, I think someone needs to ridicule the ridiculous.


Even the most astute student of science would have to admit that the concept of where life began on Earth isn't proven. It's just a theory. We've seen evidence of evolution, so we know evolution exists. However, there is no second successfully reproduced experiment of Earth to see if the theory is correct. We keep finding potential candidates, but none have proven the theories yet.

At this point, the omniscient creator is not any less provable. While it might sound ridiculous, there's no more proof for other ideas. After all, even if you subscribe to the Big Bang, where did all of that mass that went Bang! come from?


> we know for a fact that life and speciation didn't just appear ex-nihilo

Man takes a few years of school, reads a few books, and thinks he has a comprehensive idea of what happened supposedly millions of years ago.

Where were you when the earth was formed?


Man shits on school, books and descends into solipsism after reading about an idea he doesn't favor.


> Honestly, I think someone needs to ridicule the ridiculous.

Imagine thinking that Galileo was pushing a remotely modern model of planetary motion when the Copernican model still had crystal spheres and perfect circles due to lack of several centuries of research into matters like gravity.

There where easily observable flaws on both sides of the argument.


Aww, you ruined it.




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