APOD: Tutulemma: Solar Eclipse Analemma (2013 Dec 22)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 4308
Joined: Fri Dec 04, 2009 3:27 am

APOD: Tutulemma: Solar Eclipse Analemma (2013 Dec 22)

Post by APOD Robot » Sun Dec 22, 2013 5:11 am

Image Tutulemma: Solar Eclipse Analemma

Explanation: If you went outside at exactly the same time every day and took a picture that included the Sun, how would the Sun's position change? With great planning and effort, such a series of images can be taken. The figure-8 path the Sun follows over the course of a year is called an analemma. Yesterday, the Winter Solstice day in Earth's northern hemisphere, the Sun appeared at the bottom of the analemma. Analemmas created from different latitudes would appear at least slightly different, as well as analemmas created at a different time each day. With even greater planning and effort, the series can include a total eclipse of the Sun as one of the images. Pictured is such a total solar eclipse analemma or Tutulemma - a term coined by the photographers based on the Turkish word for eclipse. The above composite image sequence was recorded from Turkey starting in 2005. The base image for the sequence is from the total phase of a solar eclipse as viewed from Side, Turkey on 2006 March 29. Venus was also visible during totality, toward the lower right.

<< Previous APOD This Day in APOD Next APOD >>
[/b]

ta152h0
Schooled
Posts: 1387
Joined: Mon Aug 29, 2005 12:46 am
Location: Auburn, Washington, USA

Re: APOD: Tutulemma: Solar Eclipse Analemma (2013 Dec 22)

Post by ta152h0 » Sun Dec 22, 2013 5:21 am

wonder if any ancient astronomer discovered the sun traces a figure 8 in the sky and recorded such discovery ?
Wolf Kotenberg

User avatar
Chris Peterson
Abominable Snowman
Posts: 15936
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Tutulemma: Solar Eclipse Analemma (2013 Dec 22)

Post by Chris Peterson » Sun Dec 22, 2013 6:09 am

ta152h0 wrote:wonder if any ancient astronomer discovered the sun traces a figure 8 in the sky and recorded such discovery ?
The problem is, you need a good clock. Ancient astronomers based the time on the position of the Sun. It wasn't until we regularized time that the analemma became apparent.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
Nitpicker
Inverse Square
Posts: 2692
Joined: Fri Sep 20, 2013 2:39 am
Location: S27 E153

Re: APOD: Tutulemma: Solar Eclipse Analemma (2013 Dec 22)

Post by Nitpicker » Sun Dec 22, 2013 7:08 am

Chris Peterson wrote:
ta152h0 wrote:wonder if any ancient astronomer discovered the sun traces a figure 8 in the sky and recorded such discovery ?
The problem is, you need a good clock. Ancient astronomers based the time on the position of the Sun. It wasn't until we regularized time that the analemma became apparent.
I suspect that the more accurate water clocks developed in ancient times, were accurate enough over a 24 hour period, such that the analemma may have been noticeable via a sundial. Indeed, it seems the more sophisticated water clocks were actually calibrated to sundials (probably because the ancient bean counters used sundials).

More accurate clocks were needed much later to solve the longitude problem, where ships at sea needed the precise time for periods of weeks or months.

(Very cool analemma by the way. Not just for the eclipse, but also the twisty water slide in the foreground.)

Cecil
Asternaut
Posts: 1
Joined: Sun Dec 22, 2013 10:34 am

Analemma

Post by Cecil » Sun Dec 22, 2013 10:45 am

I like the analemma including an eclipse, but I see that it has 30 images in it. If there are two per month, why are there six extra ones ?

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18070
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

A long wabefore it, and a long wabehind it

Post by neufer » Sun Dec 22, 2013 2:23 pm

Nitpicker wrote:
Chris Peterson wrote:
ta152h0 wrote:
wonder if any ancient astronomer discovered the sun traces a figure 8 in the sky and recorded such discovery ?
The problem is, you need a good clock. Ancient astronomers based the time on the position of the Sun. It wasn't until we regularized time that the analemma became apparent.
I suspect that the more accurate water clocks developed in ancient times, were accurate enough over a 24 hour period, such that the analemma may have been noticeable via a sundial. Indeed, it seems the more sophisticated water clocks were actually calibrated to sundials (probably because the ancient bean counters used sundials).
http://en.wikipedia.org/wiki/Vitruvius wrote:
<<Marcus Vitruvius Pollio (born c. 80–70 BC, died after c. 15 BC) was a Roman author, architect, and engineer during the 1st century BC perhaps best known for his multi-volume work entitled De Architectura. A small lunar crater has been named after Vitruvius and also an elongated lunar mountain Mons Vitruvius close-by. This crater was near the valley that served as the landing site of the Apollo 17 mission.>>
http://www.gutenberg.org/files/20239/20239-h/29239-h.htm#Page_270 wrote:
[img3="analemma: from Greek ἀνάλημμα "pedestal of a sundial""]http://www.gutenberg.org/files/20239/20 ... /056th.jpg[/img3]

VITRUVIUS: THE TEN BOOKS ON ARCHITECTURE
CHAPTER VII: THE ANALEMMA AND ITS APPLICATIONS

1. In distinction from the subjects first mentioned, we must ourselves explain the principles which govern the shortening and lengthening of the day. When the sun is at the equinoxes, that is, passing through Aries or Libra, he makes the gnomon cast a shadow equal to eight ninths of its own length, in the latitude of Rome. In Athens, the shadow is equal to three fourths of the length of the gnomon; at Rhodes to five sevenths; at Tarentum, to nine elevenths; at Alexandria, to three fifths; and so at other places it is found that the shadows of equinoctial gnomons are naturally different from one another.

2. Hence, wherever a sundial is to be constructed, we must take the equinoctial shadow of the place. If it is found to be, as in Rome, equal to eight ninths of the gnomon, let a line be drawn on a plane surface, and in the middle thereof erect a perpendicular, plumb to the line, which perpendicular is called the gnomon. Then, from the line in the plane, let the line of the gnomon be divided off by the compasses into nine parts, and take the point designating the ninth part as a centre, to be marked by the letter A. Then, opening the compasses from that centre to the line in the plane at the point B, describe a circle. This circle is called the meridian.
...............................
7. This having been drawn and completed, the scheme of hours is next to be drawn on the baseplates from the analemma, according to the winter lines, or those of summer, or the equinoxes, or the months, and thus many different kinds of dials may be laid down and drawn by this ingenious method. But the result of all these shapes and designs is in one respect the same: namely, the days of the equinoxes and of the winter and summer solstices are always divided into twelve equal parts. Omitting details, therefore,—not for fear of the trouble, but lest I should prove tiresome by writing too much,—I will state by whom the different classes and designs of dials have been invented. For I cannot invent new kinds myself at this late day, nor do I think that I ought to display the inventions of others as my own. Hence, I will mention those that have come down to us, and by whom they were invented.
Nitpicker wrote:
(Very cool analemma by the way. Not just for the eclipse, but also the twisty water slide in the foreground.)
`I can explain all the poems that were EVER invented -- and a good many that haven't been invented just yet.'

This sounded VERy hopeful, so Owlice repeated the first VERsE:
  • `Twas brillig, and the slithy toves
    Did gyre and gimble in the wabe;
    All mimsy were the borogoves,
    And the mome raths outgrabe.
`That's enough to begin with,' Humpty Dumpty interrupted: `there are plenty of hard words there. "Brillig" means four o'clock in the afternoon -- the time when you begin broiling things for dinner.'

`That'll do very well,' said Owlice: and "slithy"?'

`Well, "slithy" means "lithe and slimy." "Lithe" is the same as "active." You see it's like a portmanteau -- there are two meanings packed up into one word.'

`I see it now,' Owlice remarked thoughtfully: `and what are "toves"?'

`Well, "toves" are something like badgers -- they're something like lizards -- and they're something like corkscrews.'

`They must be very curious looking creatures.'

`They are that,' said Humpty Dumpty: `also they make their nests under sun-dials -- also they live on cheese.'

`Andy what's the "gyre" and to "gimble"?'

`To "gyre" is to go round and round like a gyroscope. To "gimble" is to make holes like a gimblet.'

`And "the wabe" is the grass-plot round a sun-dial, I suppose?' said Owlice, surprised at her own ingenuity.

`Of course it is. It's called "wabe," you know, because it goes a long way before it, and a long way behind it -- '

`And a long way beyond it on each side,' Owlice added.
Last edited by neufer on Sun Dec 22, 2013 5:58 pm, edited 1 time in total.
Art Neuendorffer

User avatar
Chris Peterson
Abominable Snowman
Posts: 15936
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Tutulemma: Solar Eclipse Analemma (2013 Dec 22)

Post by Chris Peterson » Sun Dec 22, 2013 2:47 pm

Nitpicker wrote:I suspect that the more accurate water clocks developed in ancient times, were accurate enough over a 24 hour period, such that the analemma may have been noticeable via a sundial. Indeed, it seems the more sophisticated water clocks were actually calibrated to sundials (probably because the ancient bean counters used sundials).
But a sundial hides the analemma. Art's reference is interesting, but recognizing that the equinoctial gnomon shadow changes with location isn't precisely the same as recognizing the full geometrical nature of the analemma. Until accurate mechanical clocks appeared a few hundred years ago, all clocks were referenced to the Sun, typically defining the local meridian crossing as noon. So by definition, the same time each day couldn't show the lateral component of the analemma, only the longitudinal one (which is what the Vitruvius reference describes, and what assorted ancient meridian instruments would have shown).

I don't believe modern figure-eight analemmas showed up on maps and sundials until the 18th century.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
alter-ego
Serendipitous Sleuthhound
Posts: 925
Joined: Mon Apr 21, 2008 4:51 am
Location: Redmond, WA

Re: APOD: Tutulemma: Solar Eclipse Analemma (2013 Dec 22)

Post by alter-ego » Sun Dec 22, 2013 9:40 pm

Nitpicker wrote:I suspect that the more accurate water clocks developed in ancient times, were accurate enough over a 24 hour period, such that the analemma may have been noticeable via a sundial. Indeed, it seems the more sophisticated water clocks were actually calibrated to sundials (probably because the ancient bean counters used sundials).
It's true that our observation precision for determining celestial object positions predate our ability to measure time precisely. I estimate the order of timing precision needed to detect the figure 8 analemma is ~10-4, or about 10 seconds per day. Depending on one's ability measure the sun's position determines how long that timing accuracy is needed. So allowing for a reasonable ¼° solar position accuracy (½ solar diameter) and a maximum solar longitudinal drift rate of ~5 arcminutes per day around the equinox then we'd need about 3 days. However, regardless of the time required between observations to detect a solar position change, the 10-sec per day timing certainty is about half of the solar drift rate (20 seconds of time per day). For "ancient" water clocks, the drift rate is highly sensitive to temperature (to name one) which affects viscosity. An estimate yields ~30 minutes a day variation per °C variation about room temperature. In practice, I'd say a water clock is accurate on relatively short time scales (hours), but could in no way reach the accuracy needed for determining the Equation of Time.
Chris Peterson wrote: ... I don't believe modern figure-eight analemmas showed up on maps and sundials until the 18th century.
Yup, that is a pretty solid assessment. The first longer-term accurate clocks (applicable to EOT measurements) were pendulum clocks. In the latter 1600s, Christian Huygens made a pendulum clock having a first-ever accuracy of ~10 sec per day. As far as the familiar EOT analemma, Jean Paul Grandjean de Fouchy has been cited credit for it in 1740 (Of Analemmas, Mean Time and the Analemmatic Sundial). It is very consistent that the EOT knowledge and figure-8 graphical representation developed during the late 17th and early 18 century.
A pessimist is nothing more than an experienced optimist

User avatar
Nitpicker
Inverse Square
Posts: 2692
Joined: Fri Sep 20, 2013 2:39 am
Location: S27 E153

Re: APOD: Tutulemma: Solar Eclipse Analemma (2013 Dec 22)

Post by Nitpicker » Sun Dec 22, 2013 10:18 pm

alter-ego wrote:
Nitpicker wrote:I suspect that the more accurate water clocks developed in ancient times, were accurate enough over a 24 hour period, such that the analemma may have been noticeable via a sundial. Indeed, it seems the more sophisticated water clocks were actually calibrated to sundials (probably because the ancient bean counters used sundials).
It's true that our observation precision for determining celestial object positions predate our ability to measure time precisely. I estimate the order of timing precision needed to detect the figure 8 analemma is ~10-4, or about 10 seconds per day. Depending on one's ability measure the sun's position determines how long that timing accuracy is needed. So allowing for a reasonable ¼° solar position accuracy (½ solar diameter) and a maximum solar longitudinal drift rate of ~5 arcminutes per day around the equinox then we'd need about 3 days. However, regardless of the time required between observations to detect a solar position change, the 10-sec per day timing certainty is about half of the solar drift rate (20 seconds of time per day). For "ancient" water clocks, the drift rate is highly sensitive to temperature (to name one) which affects viscosity. An estimate yields ~30 minutes a day variation per °C variation about room temperature. In practice, I'd say a water clock is accurate on relatively short time scales (hours), but could in no way reach the accuracy needed for determining the Equation of Time.
Chris Peterson wrote: ... I don't believe modern figure-eight analemmas showed up on maps and sundials until the 18th century.
Yup, that is a pretty solid assessment. The first longer-term accurate clocks (applicable to EOT measurements) were pendulum clocks. In the latter 1600s, Christian Huygens made a pendulum clock having a first-ever accuracy of ~10 sec per day. As far as the familiar EOT analemma, Jean Paul Grandjean de Fouchy has been cited credit for it in 1740 (Of Analemmas, Mean Time and the Analemmatic Sundial). It is very consistent that the EOT knowledge and figure-8 graphical representation developed during the late 17th and early 18 century.

That's a pretty strong argument alter-ego. I no longer so strongly suspect that the analemma was noticed in ancient times.

ta152h0
Schooled
Posts: 1387
Joined: Mon Aug 29, 2005 12:46 am
Location: Auburn, Washington, USA

Re: APOD: Tutulemma: Solar Eclipse Analemma (2013 Dec 22)

Post by ta152h0 » Sun Dec 22, 2013 10:42 pm

I was thinking the Stonehenge guys had some clue even with the belief the earth was the center of the Universe and everything else rotated around the Earth.
Wolf Kotenberg

User avatar
Anthony Barreiro
Turtles all the way down
Posts: 793
Joined: Wed May 11, 2011 7:09 pm
Location: San Francisco, California, Turtle Island

Re: APOD: Tutulemma: Solar Eclipse Analemma (2013 Dec 22)

Post by Anthony Barreiro » Sun Dec 22, 2013 11:25 pm

The extent of planning and effort required to create this image is truly impressive. Thanks so much! Well worth repeating!
May all beings be happy, peaceful, and free.