Pope Gregory VIII - of gregorian calendar fame.

[KerrAvon]

Must have had a pretty good understanding of planetary motion and the solar system generally so clearly he must have known that the earth was not the centre of the universe as was the belief at the time. So how did he manage the science v religion aspects of especially in the era of the spanish inquisition etc? Galileo was later threatened with torture for believing what Gregory VIII must have known.

[heathfield]

No doubt the person who developed of the calender, Dr Alosyius Lilius, spent quite a time explaining to the Pope how it worked. At any rate, the Pope approved of it...

http://www.whoinvente...ar-we-have-today.html

[jno]

the purpose of it was to get the days back where they belonged; easter in particular was all over the place. I doubt that Gregory cared much how it was done.

It was commissioned by a church council and sent out for comment. Some people suggested it should be based on the movements of the sun and moon but they were ignored. So it doesn't look as though Gregory was really trying to enshrine Galileo-style thinking when he approved it.

[KerrAvon]

Yes he was correcting the calendar but how did he manage to mesh what must have been heretical thinking with his own religion? This must have been good amunition for his enemies.

[jno]

No need for him to have rocket science. The calendar had got 10 days behind, but it's just as easy to explain in his terms as in ours.

We say: they miscalculated the time it takes the earth to go round the sun.

He says: they miscalculated the time it takes the sun to go round the earth.

[KerrAvon]

Yes, he must have known the truth though.

[jno]

God might have told him, who knows.

[plautus]

When Britain belatedly adopted the Gregorian calendar in 1752 it caused a bit of confusion. Some people thought that their lives had been shortened by eleven days. Russia only adopted the calendar after the revolution of 1917, which is why the October revolution actually took place in November! The Russian Orthodox Church still adheres to the Julian calendar, hence Christmas Day falling on January 6th.

[Calibax]

I don't think it's necessary to assume a heliocentric system to calculate the length of the year. The maths is pretty much the same whether the earth goes round the sun or vice versa.
As Einstein once supposedly asked "What time does Oxford arrive at this train?"

[jake-the-peg]

If you have one body orbiting another, moon and Earth say it's pretty easy to look at it from either perspective.

The problem with a geocentric cosmology comes when you look at other planets. As we overtake Mars for example it appears to go backwards in the sky. This is called retrograde motion.

Now Ptolomy and the preCopperinicans were well aware of this and proposed elaborate systems of spheres on spheres to account for it.

To be fair it was remarkable how well it worked considering how riddiculous the logic was.

Galileo dodn't even really have any proof, he just observed moons orbiting Jupiter. This could have been accomodated too but the whole geocentric system was just beyond a joke at that stage and it just came crashing down from exhaustion like the Berlin wall.

Kepler provided the maths that showed how the geocentric orbits could be calculated but. It wasn't really until Newton that a real understanding of how it all hung together was achieved.


You need to be careful about popular myths, for example the pope gave Galileo complete freedom to publish his ideas provided he put the geoocentric one alongside

Galileo was a smartar5e though and put the geocentric one in the mouth of a character who was a thinly disguised pope being made to look foolish by his ideas in comparison.

Not really surprising he got thrown in gaol!

Trouble is that doesn't make such a good story

[Calibax]

^ Jake,That's still a bit like forcing science teachers to teach creationism alongside evolution.

[jake-the-peg]

No not really

If it had happened in the 19th century I'd have agreed with you but at the time people didn't know about gravity or Newtonian mechanics.

Galileo couln't have told you why a planet moves around the Sun or answered many of the questions that you and I know.

Yes his system was simpler without epicycles and all the complications of the ptolomeic one but we judge him with the benefit of hindsight knowing he turned out to be right

[atalanta]

You don't have to understand a thing in order for it to be named after you.

[KerrAvon]

very true, who said you did?

[jno]

well, you said "he must have known..." - so what's your evidence for that?

[KerrAvon]

Of course I have no proof/evidence but anyone who can understand the issue to the degree necessary to do what he did must have worked out what was going on. For example retrograde motion among the "wandering stars" would have told him what was happening. Now he knew he was living in times where believing the wrong thing could be very bad indeed so there is every chance he had to operate a covert understanding day to day.

[jno]

but why would a pope be looking at wandering stars? It's not like you see them shooting backward and forward outside your window, you actually have to observe them with a telescope. Not a lot of people do that even now. Chances are he knew no more about how the planets worked than I do about how my car runs; he just wanted the problem fixed and hired a mechanic to do it. Ten days deleted, leap years fiddled with, and bob's your uncle.

I don't see any reason at all to suppose he knew what was happening with the stars; he was a pope, not an astronomer, and his beat was the heavens, not the skies.

[KerrAvon]

You seem to know best, I was under the impression that he was, what would today be called, an enthusiastic amateur.

[jno]

was he? He might have been. All I can really half-remember is that he was one of those who liked to give Protestants a good kicking.

He was Gregory the 13th, not 8th.