APOD: Blue Danube Analemma (2016 Jul 29)

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APOD: Blue Danube Analemma (2016 Jul 29)

Post by APOD Robot » Fri Jul 29, 2016 4:10 am

Image Blue Danube Analemma

Explanation: The Sun's annual waltz through planet Earth's sky forms a graceful curve known as an analemma. The analemma's figure 8 shape is tipped vertically at far right in this well-composed fisheye view from Budapest, Hungary. Captured at a chosen spot on the western bank of the Danube river, the Sun's position was recorded at 11:44 Central European Time on individual exposures over days spanning 2015 July 23 to 2016 July 4. Of course, on the northern summer solstice the Sun is at the top of the curve, but at the midpoints for the autumn and spring equinoxes. With snow on the ground, the photographer's shadow and equipment bag also appear in the base picture used for the composite panorama, taken on 2016 January 7. On that date, just after the winter solstice, the Sun was leaving the bottom of the beautiful curve over the blue Danube.

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by Boomer12k » Fri Jul 29, 2016 5:28 am

Awesome....

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by Cousin Ricky » Fri Jul 29, 2016 11:52 am

Have you ever gone to Google Maps to find a street view of these locations? This one was easy to find.

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by Case » Fri Jul 29, 2016 11:54 am

Haha, I tried looking it up too. The panorama covers nearly full circle, about 340°I would guess. The nearby bridge with the distinct street light poles (?) to the south seems to be the Rákóczi Bridge. The photographer seems to be located at (47.471653,19.064346). The road between him and the river is at a lower level, according to StreetView, which is more obvious from another perspective. Looks like an interesting city to visit. :ssmile:

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by vanamonde81 » Fri Jul 29, 2016 12:50 pm

Hi Case,

You are right, I was standing exactly at the position you linked. I am working in the office building visible at the right edge of the photo.

Budapest is a beautiful city indeed. If you have a free week don't hesitate to visit here, you won't regret! ;-)

György

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by mjsakers » Fri Jul 29, 2016 1:13 pm

@Cousin Ricky - Yes! This is one of my favorite things to do! Sometimes very challenging when the clues are scarce. Found this one!

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by Fred the Cat » Fri Jul 29, 2016 2:42 pm

What would life be like in a world without analemma's? Or when the Earth becomes tidally locked to the Moon?

Very boring but if the Sun, Earth and Moon were tidally locked? At least half the Earth might get to see an eclipsed moon every night. :?: And light pollution? :idea: Guess it depends on the side. 8-)
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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by Chris Peterson » Fri Jul 29, 2016 3:15 pm

Fred the Cat wrote:What would life be like in a world without analemma's?
Not much different. That would just required a highly circular orbit, and we'd lose the east/west component. A little more extreme would be to have no axial tilt, eliminating the north/south component. That would eliminate seasons, but I don't think that would change the nature of life much.
Or when the Earth becomes tidally locked to the Moon?
Now we're talking about a planet with radically different conditions. Probably with an extreme climate system. Life evolving in such a place might be quite different. Probably not the sort of place we'd expect complex lifeforms.
Chris

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by dkp » Fri Jul 29, 2016 3:16 pm

Is this a fake? Only the last image of the sun shows lens flaring. They all should.

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by PJ Veber » Fri Jul 29, 2016 3:25 pm

I think someone should pen a tune called *The Blue Danube Analemma*...

Such a great image, I had to call my hubby at work to make sure he saw it. !:]

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by neufer » Fri Jul 29, 2016 3:37 pm

https://en.wikipedia.org/wiki/Budapest#Etymology wrote:
<<"Budapest" is the combination of the city names Buda and Pest, which were united into a single city in 1873. The origins of the names Buda and Pest are obscure. Buda [may derive] from the Slavic word вода, voda ("water"), a translation of the Latin name Aquincum, which was the main Roman settlement in the region. Pest [may originate] from the Slavic word for cave (most closely related to Bulgarian and Macedonian: пещера, peștera), or oven (Bulgarian: пещ, peșt), in reference either to a cave where fires burned or to a local limekiln.>>
https://www.google.com/#q=hungarian+physicists
http://www.scientificamerican.com/artic ... of-nature/
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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by Chris Peterson » Fri Jul 29, 2016 3:38 pm

dkp wrote:Is this a fake? Only the last image of the sun shows lens flaring. They all should.
No, because all the images were exposed so the Sun would be a disk, not overexposed. But one image was exposed for the daylit scene, and for that the Sun was necessarily overexposed.

Some analemma images prevent that by shooting their foreground image at a different time of day, when the Sun is out of the field. But that produces unexpected shadows.
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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by Whiskybreath » Fri Jul 29, 2016 4:36 pm

Case wrote:... The photographer seems to be located at (47.471653,19.064346)....
So nice that a tour bus has parked on that spot. Your photography must have a lot of fans!

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by Fred the Cat » Fri Jul 29, 2016 4:53 pm

Is "analemma" a made up word for when an astrophotographer is "anal" but has a "dilemma" on what to do?

Just kidding. I do admire their fortitude and applaud the patience they all must exhibit to give us great images. :clap:
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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by SciFan1250 » Fri Jul 29, 2016 4:57 pm

My question is how can the sun, positioned towards the front of the camera cast a shadow that also falls toward the front of the camera? This defies the physics of light, does it not?

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by Chris Peterson » Fri Jul 29, 2016 5:11 pm

SciFan1250 wrote:My question is how can the sun, positioned towards the front of the camera cast a shadow that also falls toward the front of the camera? This defies the physics of light, does it not?
The laws of physics are doing just fine.

The apparent angle of shadows can be very confusing to interpret in wide angle images. What exactly is "in front" of the camera? Consider the brick road in the foreground. It is completely straight, running north-south (north on the left, south on the right). That's consistent with the images being made near local noon- the Sun is to the south, so we see it over the southern end of the road. Note the photographer's shadow. It is pointing north, and on his north, just as we'd expect. All the shadows are pointing north. This is particularly easy to see with the guard rail posts. Their shadows point north, but in this wide angle image they also appear to point in many different directions. But that's just a projection artifact.
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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by SciFan1250 » Fri Jul 29, 2016 5:40 pm

Thank you, Chris L Peterson. Now I understand what I was seeing.

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by Fred the Cat » Fri Jul 29, 2016 6:01 pm

neufer wrote:
https://en.wikipedia.org/wiki/Budapest#Etymology wrote:
<<"Budapest" is the combination of the city names Buda and Pest, which were united into a single city in 1873. The origins of the names Buda and Pest are obscure. Buda [may derive] from the Slavic word вода, voda ("water"), a translation of the Latin name Aquincum, which was the main Roman settlement in the region. Pest [may originate] from the Slavic word for cave (most closely related to Bulgarian and Macedonian: пещера, peștera), or oven (Bulgarian: пещ, peșt), in reference either to a cave where fires burned or to a local limekiln.>>
https://www.google.com/#q=hungarian+physicists
http://www.scientificamerican.com/artic ... of-nature/
That is something Art. After the Hillarious speech last night you'd think the US is the center of the universe. Our country is worthy of pride but the world makes science tick. And some people think science is square? Who knows – in some way they may be right. :wink:

Somethings are still amiss in physics. :?:
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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by neufer » Fri Jul 29, 2016 7:25 pm

Fred the Cat wrote:
neufer wrote:
That is something Art. After the Hillarious speech last night you'd think the US is the center of the universe. Our country is worthy of pride but the world makes science tick.
A lot of Budapest born & educated physicists who escaped demagogues to become Americans:
https://en.wikipedia.org/wiki/Theodore_von_K%C3%A1rm%C3%A1n wrote:
<<Theodore von Kármán (May 11, 1881 Budapest - May 6, 1963 Aachen, West Germany) was a Hungarian-American mathematician, aerospace engineer and physicist who was active primarily in the fields of aeronautics and astronautics. He is responsible for many key advances in aerodynamics, notably his work on supersonic and hypersonic airflow characterization. He is regarded as the outstanding aerodynamic theoretician of the twentieth century.>>
https://en.wikipedia.org/wiki/Leo_Szilard wrote:
<<Leo Szilard (February 11, 1898, Budapest – May 30, 1964, La Jolla, California) was a Jewish Hungarian-born physicist and inventor. He conceived the nuclear chain reaction in 1933, patented the idea of a nuclear reactor with Enrico Fermi, and in late 1939 wrote the letter for Albert Einstein's signature that resulted in the Manhattan Project that built the atomic bomb.
https://en.wikipedia.org/wiki/Eugene_Wigner wrote:
<<Eugene Paul "E. P." Wigner (November 17, 1902, Budapest - January 1, 1995 Princeton, New Jersey) was a Hungarian-American theoretical physicist and mathematician. He received half of the Nobel Prize in Physics in 1963 "for his contributions to the theory of the atomic nucleus and the elementary particles, particularly through the discovery and application of fundamental symmetry principles".>>
https://en.wikipedia.org/wiki/John_von_Neumann wrote:
<<John von Neumann (December 28, 1903, Budapest - February 8, 1957, Washington, D.C.) was a Hungarian-American pure and applied mathematician, physicist, inventor, computer scientist, and polymath. He made major contributions to a number of fields, including mathematics (foundations of mathematics, functional analysis, ergodic theory, geometry, topology, and numerical analysis), physics (quantum mechanics, hydrodynamics and quantum statistical mechanics), economics (game theory), computing (Von Neumann architecture, linear programming, self-replicating machines, stochastic computing), and statistics.>>
Art Neuendorffer

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by Fred the Cat » Fri Jul 29, 2016 7:55 pm

neufer wrote: A lot of Budapest born & educated physicists who escaped demagogues to become Americans:
I had to look up that word. Demagogue. It may soon be time to visit Hungary for a while. :roll:
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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by MarkBour » Fri Jul 29, 2016 8:37 pm

neufer wrote: A lot of Budapest born & educated physicists who escaped demagogues to become Americans ...
Thanks for that interesting list, Art. I was wondering why the Danube looked so beautifully blue. Wouldn't that mean it was star-bursting? :D But you've answered that ... we have indeed had quite a burst of physics and math stars coming from there. I did not realize that Von Neumann, one of my favorites, was born in Budapest.
Mark Goldfain

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by heehaw » Fri Jul 29, 2016 11:20 pm

MarkBour wrote:
neufer wrote: A lot of Budapest born & educated physicists who escaped demagogues to become Americans ...
Thanks for that interesting list, Art. I was wondering why the Danube looked so beautifully blue. Wouldn't that mean it was star-bursting? :D But you've answered that ... we have indeed had quite a burst of physics and math stars coming from there. I did not realize that Von Neumann, one of my favorites, was born in Budapest.
Von Neumann was one of a team: https://en.wikipedia.org/wiki/The_Martians_(scientists)

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by heehaw » Fri Jul 29, 2016 11:23 pm

Second try at that link (the story is really worth reading!)
https://en.wikipedia.org/wiki/The_Martians_(scientists) <--- if it doesn't work, it is failure of the final ) to be included. Put it in by hand!
Last edited by geckzilla on Sat Jul 30, 2016 12:10 am, edited 1 time in total.
Reason: You can add [url]www.something.com/something()[/url] and force the ) to be included.

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by geckzilla » Sat Jul 30, 2016 12:10 am

heehaw: please note the small edit to your post.
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: Blue Danube Analemma (2016 Jul 29)

Post by alter-ego » Sat Jul 30, 2016 12:28 am

Chris Peterson wrote:
Fred the Cat wrote:What would life be like in a world without analemma's?
Not much different. That would just required a highly circular orbit, and we'd lose the east/west component. A little more extreme would be to have no axial tilt, eliminating the north/south component. That would eliminate seasons, but I don't think that would change the nature of life much.
That's not quite right. A circular orbit does not eliminate east-west motion.
Orbital ellipticity is solely responsible for the asymmetry of the analemma's figure-8 shape, and it affects the magnitude of east-west motion by only ~1/3. For a perfectly circular orbit, the figure-8 is symmetric east-west and north-south. The range of solar declination remains the same, and there's only ~33% reduction in east-west motion. For a circular orbit, the equinoxes occur the intersection point, i.e. the sun is neither slow nor fast at both equinoxes. Now If only the obliquity is reduced to 0°, solar declination remains constant but the east-west motion is about 1/2 the normal range.
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