There was a nice piece on Spaceweather.com about Galileo's drawings of sunspots. He was the first to document them systematically and show that the sun rotated. The complete article is here: LINK, including a very neat animation of his daily drawings sequentially, to show the rotation.

Why today? It's his birthday (hope you sent your cards out) :wink:

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At night the stars put on a show for free (Carole King)

[I think it is tomorrow] Regardless, Happy Birthday, Dr. Galilei (well, he should be a PhD by honorarium).

His claim to sunspots, I think, got him into a fight with another with similar claim.

Sunspots were known prior to this time due to direct observations during unusual foggy-type days. A reduction of about 10,000 to 100,000 of the intensity allows for the eye to observe features (assuming steady atmospheric conditions). [Of course, it's true color would not be revealed due to atmospheric bleaching, as usual. But, that's another subject of enormously little proportions. ]

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

I have personally observed sunspots with my unaided eye in foggy conditions. Galileo was not even close to the first to observe them.

http://www.uh.edu/engines/epi321.htm

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When I am done here I think I will go create something from metal.

But Galileo was the first to see them in any detail, correct?

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Moraliser Overtax Porn

Yeah, simply be being able to go beyond the naked-eye view. He also drew interesting physical conclusions from tracking them day-to-day, something seldom possible for naked-eye spots when you needed just the right weather conditions to see the. He could show that they lie on the surface of the Sun rather than above it (since the follow a sine law of distance from the center with time), and that we see the rotational axis of the Sun from different directions at different times of year, which he argued as indirect evidence for heliocentricity.

He made what may be considered, in hindsight, as a career-limiting move by picking a priority dispute over sunspots with the Jesuit Christoph Scheiner, who had obtained a telescope upon hearing of Galileo's work, and began observing them as early as 1611. Scheiner eventually (after about 20 years!) came to agree that sunspots were on the surface rather than foreground objects, a break with one implication of the perfection of the heavens which had sneaked into Church dogma at the time (and to which Scheiner had started out subscribing wholeheartedly).

I was under the impression that the real sticking point between Galileo and the church was over the moons of Jupiter. They were conclusive proof that not everything revolved around the Earth and therefore the Earth did not enjoy special status in the universe as created by God.

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When I am done here I think I will go create something from metal.

He was the first to establish this (1613). Scheiner was, apparently, cautioned to use a pseudonym (Apelles) with his sunspot work of 1612 so as not to "spot" the Jesuits in case of error. (Something I should have thought of before I joined up with this outfit :wink: ). It was suspected, and hoped by the Jesuits, apparently, the spots were the result of planetary transits. Keep in mind that the universe was made perfect by a God of perfection, in their view. Therefore, spots on the Sun were not anticipated.

Interesting, but I don't get it. Is a wobbling Sun difficult for a geocentric view or am I missing something? #-o

As I see it, the sunspots (on the Sun) issue was like a jab, and the moons of Jupiter were like a hard left hook.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

BUMP!

Since this is more of a thread regarding history, I think a bump should be ok.

We have gone off-topic in the Ultimate Astronomy Quiz regarding sunspots and it should fit fine in this thread.

Note that the line of travel for the sunspots in the above drawing, which we can't see , is more than the 7.5 deg. actual axial tilt of the Sun. But the point is still the same, I suppose.

However, both the Geocentric model and the heliocentric model will allow for this, contrary to Galileo's apparent claim (assuming the Solar axis always points in the same sideral direction). It is a relative issue and one can simply jump from one of these two reference frames and see the same results?

Am I wrong?

Good luck. GO SPURS! [Basketball playoffs]

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Nah, Finland lost to Canada 6-3. But it was an interesting game!
Here's a copy of my post from Quitz-thread with Topper's diagram:


Sorry, I wasn't too clear about what I ment with the direction of sunspots. As they rotate on Sun's disk there's a yearly pattern in their direction of movement as:
(image: David Topper - "Quirky Sides of Scientists")

This is discussed in the fourth day of Galileo's Dialogue. This yearly pattern is easily explained in heliocentric model, but geocentric model needs to add four different movements for Sun. David Topper says it much more clear than I could:


It's 1 in the morning here, gotta get some sleep. I'll read this thread (and Dialogue) and elaborate more on this tomorrow. And I just realized that I was wrong when I said that geocentric model needs to add four different movements for Sun - it needs to add two, so it's four movements combined.

I see little difference with these drawings than what we would see today if Saturn's rings were one fat and narrow ring casting a shadow onto the Saturn disk. This would be independent of orbit around the Sun, except we need to be Saturn in all four of its orbital quadrants.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Wow, that much? Why isn't it in the Axial tilt of major celestial bodies, on the Axial Tilt wiki page? Or on the PlanetScapes Sun page?
Isn't Topper's book a discussion of misconceptions by scientists?

Yeah, I don't get it why the tilt of Sun's rotational axis is so often omitted. Here's a demo applet: http://www.jgiesen.de/sunrot/index.html

AFAIK the first to discover it was Scheiner by observing sunspots. Here's a figure from his Rosa Ursine sive solis. It depicts two sets of sunspot-observations made six months apart. Sun's tilted axis and it's apparent change are marked with lines.




Yes, it's a look at scientist's misconceptions, mistakes and even dishonesty but also ingenuity. Most often the devil is in the details and that's why Topper's treatment on some subjects is meticulous. It's a good read and it gives a different view of history of science and astronomy - and of scientists who made that history.

Ok, no. It may be slightly less at 7.25 deg.

This is yet another irritant issue between Galileo and Scheiner. I think it was in Galileo's Dialogue which published shortly after the Rosa Ursine. It is unlikely, however, that Galileo could have inserted it since any change would have likely disrupted the extensive license process he had to go through to get Dialogue approved. [Added: it is a very important issue, however, since Galileo used the obvserved sunspot path variation as evidence for the heliocentric model. I stil don't know why he would, though.]

Yet, I think the Rosa took almost a decade to complete and publish, so perhaps Galileo heard of it during that time. I am curious what else is known about it.

The Jesuit scholars were very favorable to Galileo until he later stepped on their toes. Once Scheiner came to Rome, things got worse due to his intense disdain for Galileo and especially the publication of his Dialogue.

[I might have time tonight to look into this a little closer.]

That is an impressive drawing and the angles look fairly accurate.

Here is a 7.25 deg. axial tilt: [note the false false color depiction ]

Attached Images

Solar Axial Tilt.jpg (71.9 KB, 6 views)

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

I've found some copies of the Dialogues on the net, and one that says it's complete is missing Day Four, but it explains that's the part about tides. (And, apparently, about this subject) IIRC, Galileo asserted that there would be only one tide per day--which might have fueled some ire. He suffered from the lack of strong Med tides.

I have had a chance to learn a little more about how Galileo saw the tides from Drake's book, which I haven't finished, so I'm still learning.

He delayed Dialogues for many years for many reasons such as his work with civil engineers and lengthy health problems. [One amusing project came from a completed job that ran a water line over a tall hill but it would not syphon. The engineer complained that the water ran down the line on both sides of the hill. Galileo told them they should have contacted him before building since he knew the highest allowable hill could only be about 30 feet. ]

As I see it so far, subject to change, Galileo was convinced that tides were due to water build-up onto the shores. He invisioned that there was a differential force created between the Earth's near side and far side to the Sun. As the Earth rotated, therefore, the tides would come and go. He disagreed with Kepler's Lunar assesement because the Moon's "pull" [my term] is not synchronous with the tides, though close, and he seemed to know that islands did not experience tides (so a simple Moon lifting of water would not work). He also seem to question Kepler's lack of first hand tidal experience, since Kepler was not near the coast.

I find it interest that they were each both right and wrong on certian points!

Establishing some sort of proof favoring Copernicus was a huge issue at the time. Although Galileo was very much favored and supported in his views, he was told in no uncertain terms in an edict in 1616 to not attempt to reconcile Copernicus to scripture. This allowed hypothetical or mathematical presentations, which was how de Revolutionibus easily passed censorship in 1543, thanks to the preface, written by a Lutheran, which stated the book was to be considered only hypothetical.

The variation the sunpsot directions and the tides were big arguments he used, though I haven't read muc of his Dialogue, yet. I think he pushed harder with his tidal argument later, but I could be confused on this point.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

He knew this? But, there are tides on islands. They're not Bay of Fundy tides but they're normal tides. I was disappointed with the tides in Hawaii, sure, but I'm disappointed with all tides that are anything less than Puget Sound tides

Yes, but not consistent with just a Lunar pull theory, as Kepler seemed to be positing. Galileo did get to visit with ship captains. In fact, one captain told him that his (Galileo's) 24 hour tide cycle for Lisban was incorrect, so he had to drop this as one of his arguments.

IIRC, the Bay of Fundy has a tidal resonance that piles wave upon wave as it sloshes back and forth, which is somewhat the idea Galileo had.

Galileo, it is believed, had observed water sloshing in a barge and reasoned that tides were a very similar circumstance of water building up on the shoreline, just like upon the barge's bulkhead.

As a kid, I always dreamed of surfing a tidal wave (I never heard them called tsunamis), until I discovered how slow they were. [But then I learned about tidal bores!]

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.