APOD: Kepler's House in Linz (2018 May 15)

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APOD: Kepler's House in Linz (2018 May 15)

Post by APOD Robot » Tue May 15, 2018 4:08 am

Image Kepler's House in Linz

Explanation: Four hundred years ago today (May 15, 1618) Johannes Kepler discovered the simple mathematical rule governing the orbits of the solar system's planets, now recognized as Kepler's Third Law of planetary motion. At that time he was living in this tall house on The Hofgasse, a narrow street near the castle and main square of the city of Linz, Austria, planet Earth. The conclusive identification of this residence (Hofgasse 7) as the location of the discovery of his third law is a recent discovery itself. Erich Meyer of the Astronomical Society of Linz was able to solve the historical mystery, based in part on descriptions of Kepler's own observations of lunar eclipses. A key figure in the 17th century scientific revolution, Kepler supported Galileo's discoveries and the Copernican system of planets orbiting the Sun instead of the Earth. He showed that planets move in ellipses around the Sun (Kepler's First Law), that planets move proportionally faster in their orbits when they are nearer the Sun (Kepler's Second Law), and that more distant planets take proportionally longer to orbit the Sun (Kepler's Third Law).

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by Ann » Tue May 15, 2018 5:14 am

I once read a slightly fictionalized biography on Kepler, but fictionalized or not, I believe that most of the things the book told me were true. Such as, Kepler had to put up a legal fight to save his mother from being burnt at the stake as a witch (twice, if I remember correctly); Kepler worked as a teacher, but he was so lousy at his job that all his students quit; Kepler married and had children, but at least one of his children died, and I'm not sure he had any others; Kepler had to flee from one part of Europe to another as the princes and governors of the rather small nation-states changed their religion back and forth and made Kepler's scientific studies alternatively acceptable and heretical; and it was when he was traveling to find a new safe haven that he died, at the age of 58, in an inn where he was going to spend the night.

The hardships of his life were such that you have to wonder how he could come up with his groundbreaking Third Law. But I guess he had some help from pilfering Tycho Brahe's extensive studies on planetary motion. In Scandinavia, there are some people who believe that Kepler murdered Tycho Brahe in order to get at his notebooks. Ah, my fellow Scandinavians, leave poor Kepler alone!

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by DanielP » Tue May 15, 2018 8:42 am

The house style is looking very much younger than the 16th century houses.

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by JohnD » Tue May 15, 2018 9:42 am

What an extraordinary photograph! It looks as if Hofgasse 7 looks out onto a wide square, when in fact it faces a narrow, maedieval, cobbled street! The clue is the strange upper roof edge, which is distorted by the short focus lens used to take the picture. It is a strange house, with its balconied windows on the first floor, giving the inhabitants a view down the alley each way, as if for defence, but when seen in it's actual location, it isn't that strange.
You can find it by going to Google maps for Linz and dropping the little yellow man on Hofgasse, between Hahnegasse and Altstadt, and looking east. The corner of the next building, on Hahnegasse is similarly built like a castle battlement!

JOhn
PS far more recently than Kepler's time, Ann, infant mortality was a real thing, when it hardly occurs today, in the Western World. My own great-grandfather was one of seven children, only four of which survived infancy. J.

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by orin stepanek » Tue May 15, 2018 11:08 am

Kind of like a speed limit for planets! Isn't the second and third law somewhat related? I mean if the inner planets are going faster; than ti stands to reason that the outer planets are going slower! :roll: :lol2:
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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by Mckinley » Tue May 15, 2018 11:12 am

Never forget Kepler's fourth law of planetary motion, "The world does not revolve around you!"

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by Cousin Ricky » Tue May 15, 2018 12:40 pm

Mckinley wrote:
Tue May 15, 2018 11:12 am
Never forget Kepler's fourth law of planetary motion, "The world does not revolve around you!"
That’s pretty much the Copernican principle.

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by Cousin Ricky » Tue May 15, 2018 12:43 pm

Kepler was awesome. He had a hypothesis about the structure of the Solar System, looked at Tycho’s data, the data said, “You’re wrong,” and Kepler changed his mind accordingly.

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by Ann » Tue May 15, 2018 12:51 pm

DanielP wrote:
Tue May 15, 2018 8:42 am
The house style is looking very much younger than the 16th century houses.

You never know.


The town hall of Malmö in the 16th century.
The same building today.















Maybe the house of Hofgasse 7 in Linz has also been "prettified" to look, well, prettier since the days of Kepler?

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by starsurfer » Tue May 15, 2018 1:23 pm

Is the absolute orbital speeds of planets the same?

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by Chris Peterson » Tue May 15, 2018 1:35 pm

orin stepanek wrote:
Tue May 15, 2018 11:08 am
Kind of like a speed limit for planets! Isn't the second and third law somewhat related? I mean if the inner planets are going faster; than ti stands to reason that the outer planets are going slower!
Well, depending on how you look at it, they're all related in some way. But the second and third describe different things. The second describes the way in which the speed along an orbital path is greater when the body is nearer the Sun (it doesn't consider different planets, but any single one). The third relates orbital period (which depends upon an average speed) to distance from the Sun (semimajor axis).

But sure, if you derive these laws using Newtonian gravitational theory, you can see that in both cases the increased speed is related to the increased gravitational strength as you get closer to the center.
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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by Chris Peterson » Tue May 15, 2018 1:40 pm

starsurfer wrote:
Tue May 15, 2018 1:23 pm
Is the absolute orbital speeds of planets the same?
Not sure what you mean by that. The planets are certainly moving at different speeds along their orbital paths. And per Kepler, that speed isn't even constant for any one body unless it's in a perfectly circular orbit. (Consider that the Moon travels around the Earth at about 1 km/s, while the ISS does so at about 8 km/s.)
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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by E Fish » Tue May 15, 2018 3:03 pm

Ann wrote:
Tue May 15, 2018 5:14 am
I once read a slightly fictionalized biography on Kepler, but fictionalized or not, I believe that most of the things the book told me were true. Such as, Kepler had to put up a legal fight to save his mother from being burnt at the stake as a witch (twice, if I remember correctly); Kepler worked as a teacher, but he was so lousy at his job that all his students quit; Kepler married and had children, but at least one of his children died, and I'm not sure he had any others; Kepler had to flee from one part of Europe to another as the princes and governors of the rather small nation-states changed their religion back and forth and made Kepler's scientific studies alternatively acceptable and heretical; and it was when he was traveling to find a new safe haven that he died, at the age of 58, in an inn where he was going to spend the night.

The hardships of his life were such that you have to wonder how he could come up with his groundbreaking Third Law. But I guess he had some help from pilfering Tycho Brahe's extensive studies on planetary motion. In Scandinavia, there are some people who believe that Kepler murdered Tycho Brahe in order to get at his notebooks. Ah, my fellow Scandinavians, leave poor Kepler alone!

Ann
Kepler did have a number of children. He was also married twice. His first wife (and a number of children) died during a siege on the city in which they were living because they were Protestants and this was a time where there were outright wars between the Protestants and Catholics. There was an outbreak of typhus, I believe, and while he tried to reach them, he was not allowed into the city. He had been traveling for work. He spent long years working for one of the nobility but he couldn't get the man to pay him. He was usually destitute. Even after his death, one of his sons-in-law had to bring a suit against the noble to get payment to be given.

His life was never easy. His father was a mercenary and as such abandoned the family, leaving them poor. He described his mother as cold and unloving, but he had to defend her from charges of witchcraft because it was kind of his fault. He wrote what is arguably the first science fiction novel called Somnium (The Dream) where he travels to the Moon by means of a spell cast by a woman who people decided was his mother.

He worked for Tycho Brahe and had been promised access to his data upon Tycho's death, but Tycho's family tried to keep it from him because he was of low social status. So yes, he did steal the data, but it was only because Tycho's family wouldn't fulfill the promise Tycho had made.

On top of all of this, he was said to be myopic and wrote to Galileo for information about his new telescope. He was, as stated, an ardent advocate of the Copernican system, but Galileo ignored him because he was a poor Protestant and Galileo was a wealthy Catholic.

I really feel for the guy. He had challenge after challenge and his life never seemed to be easy. His dream had been to be a priest (he was always a man of faith) but he couldn't afford to do it. That's why he studied mathematics instead.

When I teach about Galileo and Kepler, I always talk about how much I like and respect Kepler and sympathize for his hard but amazingly successful life.

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by neufer » Tue May 15, 2018 3:23 pm


https://en.wikipedia.org/wiki/Johannes_Kepler#Linz_and_elsewhere_(1612%E2%80%931630) wrote:
<<Kepler's laws of planetary motion were not immediately accepted. Several major figures such as Galileo and René Descartes completely ignored Kepler's Astronomia nova. Many astronomers, including Kepler's teacher, Michael Maestlin, objected to Kepler's introduction of physics into his astronomy. Some adopted compromise positions. Ismaël Bullialdus accepted elliptical orbits but replaced Kepler's area law with uniform motion in respect to the empty focus of the ellipse.>>
Show that for both perihelion & aphelion* an elliptical orbit does indeed result in the same ω uniform motion with respect to the empty focus of the ellipse but that ω must dip to a lower value between these extremes (with respect to the empty focus).

*The words perihelion & aphelion were coined by Johannes Kepler. The words are formed from the prefixes peri- (Greek: περί, near) and apo- (Greek: ἀπό, away from) affixed to the Greek word for the sun, ἥλιος.
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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by JohnD » Tue May 15, 2018 4:12 pm

Hang on! "Kepler's House"? That large, nay magnificent edifice on the main street of the medieval burgh of Linz? "Hof" means town hall, and a Hofgasse is not a backyard alley. That's not Kepler's "house"! He may have worked there, lodged there or had business there, but this poor, downtrodden man did NOT own that house!
Or are you constructing a different reality?
John

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by neufer » Tue May 15, 2018 5:57 pm

JohnD wrote:
Tue May 15, 2018 4:12 pm

Hang on! "Kepler's House"? That large, nay magnificent edifice on the main street of the medieval burgh of Linz? "Hof" means town hall, and a Hofgasse is not a backyard alley. That's not Kepler's "house"! He may have worked there, lodged there or had business there, but this poor, downtrodden man did NOT own that house!

Or are you constructing a different reality?
  • Hey...it's good PR; especially as compared to Hitler's House in Linz:
https://en.wikipedia.org/wiki/Linz#History wrote:
<<One important inhabitant of the city was Johannes Kepler, who spent several years of his life in the city teaching mathematics. He discovered, on 15 May 1618, the distance-cubed-over-time-squared — or 'third' — law of planetary motion. The local public university, Johannes Kepler University, is named after him. Another famous citizen was Anton Bruckner, who spent the years between 1855 and 1868 working as a local composer and organist in the Old Cathedral, Linz. The Brucknerhaus is named after him.

Adolf Hitler was born in the border town of Braunau am Inn but moved to Linz in his childhood. Hitler spent most of his youth in the Linz area, from 1898 until 1907, when he left for Vienna. The family lived first in the village of Leonding on the outskirts of town, and then on the Humboldtstrasse in Linz. After elementary education in Leonding, Hitler was enrolled in the Realschule (school) in Linz, as was the philosopher Ludwig Wittgenstein. Notorious Holocaust architect Adolf Eichmann also spent his youth in Linz. To the end of his life, Hitler considered Linz to be his "home town", and envisioned extensive architectural schemes for it, wanting it to become the main cultural centre of the Third Reich. What was once the Mauthausen-Gusen concentration camp is 20 km (12 miles) east of the city of Linz.>>
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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by heehaw » Tue May 15, 2018 7:39 pm

Kepler was awesome! When Newton said he (Newton) stood on the shoulders of giants, he was referring to Kepler and Tycho Brahe. Kepler died believing he had established his own incorrect theory of planetary motion: that the orbits fit between the 3-dimensional regular solids (cube, etc.). Kepler's three laws follow straightforwardly from Newton's law of universal gravitation. It was an incredible miracle that two such totally different geniuses lived and worked together: without their work, it is doubtful that Newton would have accomplished all he did.

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by heehaw » Tue May 15, 2018 7:48 pm

Here is what was thought, before Kepler and Copernicus: http://henry.pha.jhu.edu/pretzels.pdf

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by De58te » Wed May 16, 2018 12:43 am

Really? I had thought that when Newton had said that he stood on the shoulders of giants, that he was referring to Greeks like Euclid, Pythagoras, and Archimedes??

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by neufer » Wed May 16, 2018 2:21 am

De58te wrote:
Wed May 16, 2018 12:43 am
heehaw wrote:
Tue May 15, 2018 7:39 pm

When Newton said he (Newton) stood on the shoulders of giants, he was referring to Kepler and Tycho Brahe. Kepler died believing he had established his own incorrect theory of planetary motion: that the orbits fit between the 3-dimensional regular solids (cube, etc.). Kepler's three laws follow straightforwardly from Newton's law of universal gravitation. It was an incredible miracle that two such totally different geniuses lived and worked together: without their work, it is doubtful that Newton would have accomplished all he did.
Really? I had thought that when Newton had said that he stood on the shoulders of giants, that he was referring to Greeks like Euclid, Pythagoras, and Archimedes??
https://en.wikipedia.org/wiki/Standing_on_the_shoulders_of_giants wrote:
<<The metaphor of dwarfs standing on the shoulders of giants (Latin: nanos gigantum humeris insidentes) expresses the meaning of "discovering truth by building on previous discoveries".

Isaac Newton remarked in a letter to his rival Robert Hooke dated February 5, 1676 [O.S.] that: What Des-Cartes [sic] did was a good step. You have added much several ways, & especially in taking the colours of thin plates into philosophical consideration. If I have seen further it is by standing on the sholders [sic] of Giants.

This has recently been interpreted by a few writers as a sarcastic remark directed at Hooke's appearance. Although Hooke was not of particularly short stature, he was of slight build and had been afflicted from his youth with a severe kyphosis. However, at this time Hooke and Newton were on good terms and had exchanged many letters in tones of mutual regard. Only later, when Robert Hooke criticized some of Newton's ideas regarding optics, was Newton so offended that he withdrew from public debate. The two men remained enemies until Hooke's death.

This concept has been traced to the 12th century, attributed to Bernard of Chartres. The attribution to Bernard of Chartres is due to John of Salisbury. In 1159, John wrote in his Metalogicon: "Bernard of Chartres used to compare us to dwarfs perched on the shoulders of giants. He pointed out that we see more and farther than our predecessors, not because we have keener vision or greater height, but because we are lifted up and borne aloft on their gigantic stature."

According to medieval historian Richard William Southern, Bernard was comparing contemporary 12th century scholars to the ancient scholars of Greece and Rome: [The phrase] is not a great claim; neither, however, is it an example of abasement before the shrine of antiquity. It is a very shrewd and just remark, and the important and original point was the dwarf could see a little further than the giant. That this was possible was above all due to the cathedral schools with their lack of a well-rooted tradition and their freedom from a clearly defined routine of study.

Diego de Estella took up the quote in the 16th century; by the 17th century it had become commonplace. Robert Burton, in The Anatomy of Melancholy (1621), quotes Stella thus: I say with Didacus Stella, a dwarf standing on the shoulders of a giant may see farther than a giant himself. Later in the 17th century, George Herbert, in his Jacula Prudentum (1651), wrote "A dwarf on a giant's shoulders sees farther of the two."

Against this notion, Friedrich Nietzsche argues that a dwarf (the academic scholar) brings even the most sublime heights down to his level of understanding. In the section of Thus Spoke Zarathustra (1882) entitled "On the Vision and the Riddle", Zarathustra climbs to great heights with a dwarf on his shoulders to show him his greatest thought. Once there however, the dwarf fails to understand the profundity of the vision and Zarathustra reproaches him for "making things too easy on [him]self." If there is to be anything resembling "progress" in the history of philosophy, Nietzsche in "Philosophy in the Tragic Age of the Greeks" (1873) writes, it can only come from those rare giants among men, "each giant calling to his brother through the desolate intervals of time," an idea he got from Schopenhauer.>>
Art Neuendorffer

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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by MarkBour » Wed May 16, 2018 4:14 am

So, speaking of houses, I wonder what is the best view anyone got of asteroid 2010 WC9 tonight? (I would say it was approximately "house sized" ... okay a really big house ... okay, maybe about the size of the U.S. Capitol Building.)
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Re: APOD: Kepler's House in Linz (2018 May 15)

Post by Per Flea » Thu May 17, 2018 4:24 pm

De58te wrote:
Wed May 16, 2018 12:43 am
heehaw wrote:
Tue May 15, 2018 7:39 pm

When Newton said he (Newton) stood on the shoulders of giants, he was referring to Kepler and Tycho Brahe.
Really? I had thought that when Newton had said that he stood on the shoulders of giants, that he was referring to Greeks like Euclid, Pythagoras, and Archimedes??