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Exactly 400 years ago this day (3-8-1618)

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#1 Otto Piechowski

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Posted 08 March 2018 - 07:22 PM

"For after finding the true intervals of the spheres by the observations of Tycho Brahe and continuous labor and much time, at last the right ratio of the periodic times to the spheres and, if you want the exact time, was conceived mentally on the 8th of March in this year One Thousand Six Hundred and Eighteen...the ratio which exists between the periodic times of any two planets is precisely the ratio of the 3/2th power of the mean distances, i.e. of the spheres themselves...the true diurnal arc of each planet is to be multiplied by the semidiameter of its sphere..."  Johannes Kepler, Harmonies of the World, Great Books of the Western World, page 1020, A.D. 1952.


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#2 ShaulaB

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Posted 08 March 2018 - 07:38 PM

Let's hear it for Kepler's 3rd law of planetary motion. Yay bow.gif



#3 llanitedave

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Posted 08 March 2018 - 11:15 PM

"For after finding the true intervals of the spheres by the observations of Tycho Brahe and continuous labor and much time, at last the right ratio of the periodic times to the spheres and, if you want the exact time, was conceived mentally on the 8th of March in this year One Thousand Six Hundred and Eighteen...the ratio which exists between the periodic times of any two planets is precisely the ratio of the 3/2th power of the mean distances, i.e. of the spheres themselves...the true diurnal arc of each planet is to be multiplied by the semidiameter of its sphere..."  Johannes Kepler, Harmonies of the World, Great Books of the Western World, page 1020, A.D. 1952.

One of the greatest intuitive insights in human history!

 

To be pedantic, though I'm not sure the date is exactly 400 years ago.  Many of the Protestant European states, where Kepler lived, didn't adopt our modern Gregorian Calendar until the latter 1600's or 1700, so I suspect the date he used might have been part of the Julian Calender.  So we could be 10 days off.


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#4 Otto Piechowski

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Posted 09 March 2018 - 09:04 AM

That question, Dave, (was Kepler using the Gregorian calendar, in place from A.D. 1582 when he wrote that passage I quoted above) is interesting and relevant.

 

So, I went on line and did some searching.  Harmonies was published in A.D. 1619 while Kepler was living/working in Linz, Austria.  Kepler was probably a protestant.  In A.D. 1594 he accepted a position at the Lutheran school at Graz.  In A.D. 1598 he had to flee due to religious persecution by the Austrian bishop (Roman Catholic) of Styria(?).  Soon, thereafter, he was reinstated in his teaching position by favor of the Jesuits.  Nonetheless, in A.D. 1600 he served as Brahe's assistant at Prague.

 

Around about A.D. 1611, he moved to Linz.  Linz had been in the Lutheran part of Austria (eastern Austria) but by this time had been "re-catholicized as a result of the counter reformation.  (This re-catholicisation began around A.D. 1545.)  It was during this time, while at Linz, that his Harmonies was published. with a dedication to James 1 of England (protestant, who with his wife once visited Tycho Brahe).

 

My best guess is that due to living in a Roman Catholic area at the time of the publishing of the Harmonies, and due to the astronomical sensible-ness of the Gregorian calendar; that Kepler may have been using it when he wrote "on the 8th of March in this year One Thousand Six Hundred and Eighteen".  But, that is only a guess on my part and I would appreciate and be interested in what others have to say, especially, indicating otherwise.

 

Otto


Edited by Otto Piechowski, 09 March 2018 - 09:20 AM.


#5 llanitedave

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Posted 10 March 2018 - 03:53 AM

That question, Dave, (was Kepler using the Gregorian calendar, in place from A.D. 1582 when he wrote that passage I quoted above) is interesting and relevant.

 

So, I went on line and did some searching.  Harmonies was published in A.D. 1619 while Kepler was living/working in Linz, Austria.  Kepler was probably a protestant.  In A.D. 1594 he accepted a position at the Lutheran school at Graz.  In A.D. 1598 he had to flee due to religious persecution by the Austrian bishop (Roman Catholic) of Styria(?).  Soon, thereafter, he was reinstated in his teaching position by favor of the Jesuits.  Nonetheless, in A.D. 1600 he served as Brahe's assistant at Prague.

 

Around about A.D. 1611, he moved to Linz.  Linz had been in the Lutheran part of Austria (eastern Austria) but by this time had been "re-catholicized as a result of the counter reformation.  (This re-catholicisation began around A.D. 1545.)  It was during this time, while at Linz, that his Harmonies was published. with a dedication to James 1 of England (protestant, who with his wife once visited Tycho Brahe).

 

My best guess is that due to living in a Roman Catholic area at the time of the publishing of the Harmonies, and due to the astronomical sensible-ness of the Gregorian calendar; that Kepler may have been using it when he wrote "on the 8th of March in this year One Thousand Six Hundred and Eighteen".  But, that is only a guess on my part and I would appreciate and be interested in what others have to say, especially, indicating otherwise.

 

Otto

And we think daylight savings time is complicated!!!


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