Galilean Moons at 400

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400 years ago today, Galileo got the bright idea of taking his newly made telescope and pointing it at Jupiter. He saw some new stars, strangely in a straight line with Jupiter. Over the next couple of nights he kept looking, saw a fourth star, and then realized that the “stars” were moving with Jupiter, but not exactly. From his Starry Messenger:

On the seventh day of January in this present year 1610, at the first hour of night, when I was viewing the heavenly bodies with a telescope, Jupiter presented itself to me; and because I had prepared a very excellent instrument for myself, I perceived (as I had not before, on account of the weakness of my previous instrument) that beside the planet there were three starlets, small indeed, but very bright. Though I believed them to be among the host of fixed stars, they aroused my curiosity somewhat by appearing to lie in an exact straight line parallel to the ecliptic, and by their being more splendid than others of their size. … There were two stars on the eastern side and one to the west. The most easterly star and the western one appeared larger than the other. I paid no attention to the distances between them and Jupiter, for at the outset I thought them to be fixed stars, as I have said. But returning to the same investigation on January eight – led by what, I do not know – I found a very different arrangement. The three starlets were now all to the west of Jupiter, closer together, and at equal intervals from one another . …

On the tenth of January … there were but two of them, both easterly, the third (as I supposed) being hidden behind Jupiter . … There was no way in which such alterations could be attributed to Jupiter’s motion, yet being certain that these were still the same stars I had observed … my perplexity was now transformed into amazement. I was sure that the apparent changes belonged not to Jupiter but to the observed stars, and I resolved to pursue this investigation with greater care and attention . …

You just know that what he really said to himself here was “Holy …”

I had now decided beyond all question that there existed in the heavens three stars wandering about Jupiter as do Venus and Mercury about the sun, and this became plainer than daylight from observations on similar occasions which followed. Nor were there just three such stars; four wanderers complete their revolution about Jupiter . …

Here we have a fine and elegant argument for quieting the doubts of those who, while accepting with tranquil mind the revolutions of the planets about the sun in the Copernican system, are mightily disturbed to have the moon alone revolve about the earth and accompany it in annual rotation about the sun. Some have believed that this structure of the universe should be rejected as impossible. But now we have not just one planet rotating about another while both run through a greater orbit around the sun; our eyes show us four stars which wander about Jupiter as does the moon around the earth, while all together trace out a grand revolution about the sun in the space of twelve years.

33 Comments

PS: Here’s a scan of the original: http://contentdm.lindahall.org/cdm4[…]ISOSHOW=5292

“Science progresses most not by shouts of ‘Eureka!’ but by ‘Hmm… That’s odd.’”

Said by somebody very much smarter than me, but with a name I either can’t remember, or never knew.

The significance of this is largely forgotten now, but it had been argued that if the Earth moved it would leave the moon behind. (This was a generation before Isaac Newton described gravity’s effect on such bodies.)

But by observing that Jupiter had four moons that definitely weren’t getting left behind, one very strong argument for the geocentric universe was demolished.

It was either Asimov or Clarke…I think Clarke.

“The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ (I found it!) but ‘That’s funny …’”

The quote, in several minor variations, is attributed to Asimov consistently, but nobody online seems to have sourced it. How rude.

Check out the just-released book “Galileo’s Dream” by Kim Stanley Robinson for an intriguing story which centers around this part of Galileo’s life.

Interesting mental exercise: If Galileo hadn’t realized what his observations meant–or if the biblically approved geocentric system had been successfully maintained by the Church–where would “modern” science be today?

If we hadn’t broken with the Bible as describing physical nature, what would life be like now?

“If we hadn’t broken with the Bible as describing physical nature, what would life be like now?”

Pretty much the same, probably. If Galileo hadn’t, someone else would have. Can’t keep curiosity down, not in the long run.

YEC here. I like Galileo and insist that he never threatened or changed biblical creationism. Perhaps the Catholic church leaders didn’t like some ideas here because they accepted ideas here from the ancient Greeks. So to challenge the greeks was to challenge Church writers who they said can’t be questioned. Yet protestantism questioned al this too. This is not a case of knowledge fighting the bible but rather knowledge and freedom of knowledge fighting error in human thinking. God or Genesis was never bothered by old Gal. I am confident that if Gal was here today he would be the loudest supporter of freedom of ideas/speech/inquiry in all public institutions or private ones where the natual world is is investigated and conclusions made. He would not want creationism EXPELLED from anywhere.

For once, Byers has stumbled over a fact. Stopped watches are right once every twelve hours, and so on.

Galileo said nothing about creationism. He did demonstrate that the Earth was not the centre of the Universe, which was enough to get him threatened with a trial for heresy by the Byerses of his day, who were then in a majority. They actually showed him the instruments, as the saying goes. If he hadn’t recanted, they’d have burned him, like they did Giordani Bruno.

If Galileo were alive in Darwin’s day, or now, he would have recognised and applauded following the evidence where it led, and he would recognise in Byers the spirit of the Inquisition.

Robert Byers said:

I am confident that if Gal was here today he would be the loudest supporter of freedom of ideas/speech/inquiry in all public institutions or private ones where the natual world is is investigated and conclusions made. He would not want creationism EXPELLED from anywhere.

He would want creationism EXPELLED from public school science classes for exactly the same reason that he didn’t want the geocentric model of the solar system taught, - it was flatly contradicted by all of the evidence. That is where the freedom of ideas, speech and inquiry have lead Robert. That is what Galileo taught us. Now, if you can bring yourself to accept a sun centered solar system, why on earth can’t you accept evolution?

A wise man once said that those who refuse to learn from the lessons of history are idiots, and once again, I was right.

Anon said:

“If we hadn’t broken with the Bible as describing physical nature, what would life be like now?”

Pretty much the same, probably. If Galileo hadn’t, someone else would have. Can’t keep curiosity down, not in the long run.

I guess I wasn’t clear enough. Suppose it had NEVER happened. Suppose no science had ever been allowed to proceed beyond what some fundamentalist church approved (say, Byers’s, or FL’s, or Henry’s). Not what they would approve of today–like computers: I’m wondering if things like computers could ever have been developed if all scientists were fundies, or if the fundies got to rule on what scientists could do, or write, or teach. Would we have electricity? Internal combustion? Vaccines? Antibiotics? Modern agricultural crops? Would we even wash our hands?

If I remember little historical snippets I picked up here and there, nearly every scientific and technological advance that has made our modern life possible was opposed as the “work of Satan” or some such by fundamentalist “authorities”. Even Franklin’s lightning rods were condemned as trying to thwart the “will of God” to blast sinners with lightning.

Just Bob said:

…Suppose it had NEVER happened. Suppose no science had ever been allowed to proceed beyond what some fundamentalist church approved…

We would still be living in the worse parts of the Dark Ages, where the leading causes of death were famine, diarrhea, disease, violence, speaking your mind, and not being pious enough.

That, and the locals would still be trying to stop disasters by burning whichever hated minority is available, be it cats, old women, Jews or members of heretical sects.

It seems to me that you (R. Bayer) are missing again the point. The analogy is that Galileo was accused because he was supporting the heliocentric theory of Copernicus that was considered at that time in contrast with a “literal” interpretation of the Holy Scriptures. Galileo was obliged (otherwise he has been punished as heretic like Giordano Bruno) to abjure his opinions. The time proved Galileo right and a Pope (also if some centuries later) officially apologised for it. The Galileo’s process remains a trauma in the story of the Church, too; it burdened the relationship between religion and science for the time after. I presume that this is one of the main reasons why the Catholic Church is now very prudent in questions related to the science. By the way, the freedom of science from theology was already affirmed in the western philosophy later during the Enlightenment (about two centuries ago). So you can understand that the re-proposition of old thesis (literal interpretation of the Bible, submission of science to theology, etc.) stinks of mould.

Sorry, I mean R. Byers.

Byers should read Galileo’s letter to the Grand Dutchess Christina.

It describes pretty accurately the fundamentalist mindset we see today among the anti-evolution and anti-science crowd. Byers would find himself in that crown Galileo criticized.

C’mon everyone, stop entertaining Robert. If you must talk to a “YEC”, FL is IMO infinitely more interesting.

Its SHOULD be noted that Galilei was NOT the first telescopic observer. It has only recently been discovered that Thomas Harriot

http://www.ras.org.uk/index.php?opt[…]amp;Itemid=2

Germanicus said:

It seems to me that you (R. Bayer) are missing again the point. The analogy is that Galileo was accused because he was supporting the heliocentric theory of Copernicus that was considered at that time in contrast with a “literal” interpretation of the Holy Scriptures. Galileo was obliged (otherwise he has been punished as heretic like Giordano Bruno) to abjure his opinions. The time proved Galileo right and a Pope (also if some centuries later) officially apologised for it. The Galileo’s process remains a trauma in the story of the Church, too; it burdened the relationship between religion and science for the time after. I presume that this is one of the main reasons why the Catholic Church is now very prudent in questions related to the science. By the way, the freedom of science from theology was already affirmed in the western philosophy later during the Enlightenment (about two centuries ago). So you can understand that the re-proposition of old thesis (literal interpretation of the Bible, submission of science to theology, etc.) stinks of mould.

to you and everyone I’m not missing the point. I see the point here as a simple equation. People in power or inclination try to stop or EXPELL important ideas on things that are important beyond themselves. The Catholic church tried to stop a threat to their idea of origins. Today the establishment tries to stop creationism(s) because they are a threat to their ideas on origins and surely bigger conclusions of the order of things.

As a Evangelical Protestant it means nothing to me for error in the Catholic church. (I do believe Luther was hostile too but thats just his opinion) Yet the matter is does any thing of accuracy here deny Genesis. We say no. We welcome investigators who prove their stuff. Galileo is with us and i suspect he believed in a God creation. God and Genesis is never threatened by science but is by human intents and powers trying to stand against freedom of inquiry whether it leads. I am still confident old Gal would keenly oppose the modern censorship of creationism in public schools on origin issues where ther is great or a lot of disagreement in public convictions.

And you miss the point that saying a person is wrong because that person’s claim contradicts observed reality does not and never did equal persecution.

In order to claim similarity with Galileo Galilei, one’s claims must first match with observed reality.

Robert wrote:

“to you and everyone I’m not missing the point. I see the point here as a simple equation. People in power or inclination try to stop or EXPELL important ideas on things that are important beyond themselves. The Catholic church tried to stop a threat to their idea of origins. Today the establishment tries to stop creationism(s) because they are a threat to their ideas on origins and surely bigger conclusions of the order of things.”

you are still missing the point the church denied reality the evidence was all that mattered you still have not learned the lesson demanding evidence is not persecution demanding evidence is not EXPELLING anyone demansing evidence is the point deal with it

to you and everyone I’m not missing the point. I see the point here as a simple equation. People in power or inclination try to stop or EXPELL important ideas on things that are important beyond themselves. The Catholic church tried to stop a threat to their idea of origins.

What idea of “origins?” The location of the Earth relative to everything else? The motion of the sun relative to the Earth? That’s not “origins,” that’s astronomical geography. I really wish you wouldn’t type or EXPELL this kind of nonsense into the web, it only makes you look bonkers.

Today the establishment tries to stop creationism(s) because they are a threat to their ideas on origins and surely bigger conclusions of the order of things.

What if “Creationism” just does not work? What then?

MACROEVOLUTIONISTS THINK BECAUSE THEY CAN SEE DOTS ON THE TELESCOPE MOVING BACK AND FORTH AGAINST THE BACKGROUND OF JUPITER THAT JUPITER DOESN’T REVOLVE AROUND THE EARTH BUT INSTEAD REVOLVES AROUND THE SUN AND THAT THE EARTH DOES TOO–WHAT A MORONIC NON-SEQUITUR! IF THE EARTH WAS REVOLVING AROUND THE SUN WE WOULD BE THROWN OFF! WHAT A BUNCH OF MORONS!

Can someone put a muzzle on the moron Yum?

Galileo is with us and i suspect he believed in a God creation.

more delusional and irrelevant ranting from byers.

next.

If Galileo were alive in Darwin’s day, or now, he would have recognized and applauded following the evidence where it led, and he would recognize in Byers the spirit of the Inquisition.

the only real danger with people like Byers, is that they themselves fail to recognize it, even as they apply it.

otherwise they would be harmless idiots.

Stanton said:

Can someone put a muzzle on the moron Yum?

IMO, “yum install Jesus” is trolling in the most classic sense – posting outrageous stuff strictly to stir up trouble. Stop feeding him and he’ll probably go away. Regardless, he is completely ignorable and not worth responding to.

SWT said:

Stanton said:

Can someone put a muzzle on the moron Yum?

IMO, “yum install Jesus” is trolling in the most classic sense – posting outrageous stuff strictly to stir up trouble. Stop feeding him and he’ll probably go away. Regardless, he is completely ignorable and not worth responding to.

Well, at least he makes a good case that he should be thrown off the earth.

Byers, your problem is that “freedom of inquiry” has NEVER lead to God; it has always led to science and a lack of God.

Unfortunately, you’re too closed-minded to understand that point, but it’s worth making anyway: freedom of inquiry has never, ever pointed to the hand of God.

And if I could learn to spell, I could someday be a great and important scientist. Like Galileo. That would be “led” to God.

Sigh.

Though I’d like to have a creationist support this claim at some point: that given a situation of “free inquiry”, examination of a problem logically led to the conclusion that it had a supernatural explanation.

Rilke’s granddaughter said:

Sigh.

Though I’d like to have a creationist support this claim at some point: that given a situation of “free inquiry”, examination of a problem logically led to the conclusion that it had a supernatural explanation.

That would entail actual research and or study.

And doing research or cladestine studying are abominations in the eyes of creationists: horrifying acts that waste time much better spent lying to and browbeating others in order to make Jesus proud (somehow).

Stanton said:

That would entail actual research and or study.

And doing research or cladestine studying are abominations in the eyes of creationists…

Well duh!

Research is dangerous. You never know when your experiment will turn up a result at odds with established dogma.

While novel results are joyous thing in actual science (Oh Boy! Something new and unexpected!) those pesky, pesky, experimental facts are the worst thing possible to creationists because they must come up with yet another nonsensical rationalization to fill the new gap between their existing nonsensical rationalizations (I call this mode of argument the “god of the crap” system).

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This page contains a single entry by Nick Matzke published on January 7, 2010 1:01 PM.

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