APOD: Through a Sun Tunnel (2011 Dec 22)

Comments and questions about the APOD on the main view screen.
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APOD: Through a Sun Tunnel (2011 Dec 22)

Post by APOD Robot » Thu Dec 22, 2011 5:06 am

Image Through a Sun Tunnel

Explanation: Today the Sun stands still at 05:30 UT. Halting its steady march toward southern declinations and begining its annual journey north, the event is known as a solstice. In the northern hemisphere December's solstice marks the astronomical start of winter. And if you're in the Great Basin Desert outside of Lucin, Utah, USA, near solstice dates you can watch the Sun rise and set through Sun Tunnels. A monumental earthwork by artist Nancy Holt, the Sun Tunnels are constructed of four 9 foot diameter cast concrete pipes each 18 feet long. The tunnels are arranged in a wide X to achieve the solstitial sunset and sunrise alignments. In this dramatic snapshot through a Sun Tunnel the Sun is just on the horizon. The cold, cloudy sunset was near the 2010 winter solstice. During daylight hours, holes in the sides of the pipes project spots of sunlight on their interior walls, forming a map of the principal stars in the constellations Draco, Perseus, Columba, and Capricorn. Fans of planet earthworks and celestial landart should note that the Sun Tunnels are about 150 miles by car from Robert Smithson's (Holt's late husband) Spiral Jetty.

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by Jeebo » Thu Dec 22, 2011 6:15 am

About the solstice and the beginning of winter, or any other season. I've often wondered why the solstices and equinoxes mark the beginning of the seasons. It seems to me that they really mark the midpoint of the season. Take the winter solstice in the northern hemisphere, for example. The winter would be the one-fourth of the solar year that has the least daylight and most night, wouldn't it? And the winter solstice is actually the midpoint of that one-fourth year period. The days are getting shorter and the nights longer approaching the winter solstice, and then the days start getting longer and the nights shorter after the solstice. The cumulative daylight adds up to less during those 91+ days that the solstice is in the middle of, than it does during the 91+ days after the solstice.

Ron

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by Chris Peterson » Thu Dec 22, 2011 6:21 am

Jeebo wrote:About the solstice and the beginning of winter, or any other season. I've often wondered why the solstices and equinoxes mark the beginning of the seasons. It seems to me that they really mark the midpoint of the season.
It isn't a universal practice for seasons to officially start on the solstices and equinoxes. Different countries use different systems.

While the solstices and equinoxes are logical middle dates if you think of the seasons in terms of day length, most people think of them in terms of temperature. In the temperate latitudes (where most people live), temperatures lag the solstices by about 6 weeks- that is, in the north we can expect the coldest part of winter in early February, and the hottest part of summer in early August. So by that rule, starting the seasons on the solstices makes pretty good sense.
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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by frankb4now » Thu Dec 22, 2011 7:54 am

I do believe this is a picture of a sunrise. If this is a sunset, it would suggest that North is to the right and somehow that would seem to impede the use of the star holes on the right side of the nearest tunnel.
Maybe the photo negative was reversed....and maybe I'm just plain wrong?

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by JohnD » Thu Dec 22, 2011 10:12 am

It's pointless asking 'why' an artist did it this way, but if it had been me, I would have used a lot more pipe.
Seeing the sunrise at the end of a long, dark tunnel has more impact than if one is surrounded by open air, peering down a pipe. The idea of the constellations bored in the sides would have worked better and there could have been many more.

But even artists must do what their budget allows.
JOhn

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by Astronymus » Thu Dec 22, 2011 11:23 am

In 5000 years scientists will ask what this construction was made for. :lol:

ruben

Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by ruben » Thu Dec 22, 2011 12:03 pm

Me han dado una gran idea. Vivo en un lugar en que aprecio todo el horizonte al amanecer. 21 de junio - 21 de diciembre. Colocaré varios tubos con retícula. Dos veces al año el Sol aparecerá allí. Gracias. Muchas gracias.

Google translation added by admin: They have given me a great idea. I live in a place that I appreciate all the horizon at dawn. June 21 - December 21. Grid will place several tubes. Twice a year the Sun will appear there. Thank you. Thank you very much.
Last edited by owlice on Thu Dec 22, 2011 12:06 pm, edited 1 time in total.
Reason: added translation

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by starstruck » Thu Dec 22, 2011 12:48 pm

Yay! ♫♪♫ here comes the sun, dee-de-doo-dah! ♪♪♫ here comes the sun, and I say it's alright! ♪♫♪♪♫

Hmm, of course I'm imagining this, but the sun definitely feels warmer today . . and it looks a smidgen higher in the sky too :D

I'm doubtful those concrete pipes will last as long out there in the Utah desert as Stonehenge on Salisbury Plain, but nice work! *

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by FloridaMike » Thu Dec 22, 2011 12:58 pm

I want one!

none

Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by none » Thu Dec 22, 2011 12:59 pm

Hey! Are these pipes in the movie "the book of Eli"? Never did understand what they were in that movie.

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by orin stepanek » Thu Dec 22, 2011 1:06 pm

none wrote:Hey! Are these pipes in the movie "the book of Eli"? Never did understand what they were in that movie.
I think they are sewer pipes that the artists had a unique idea for; now they are a modern day stone henge. :mrgreen:
Orin

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by TMart » Thu Dec 22, 2011 2:56 pm

Does the photographer have any more details regarding lighting and time of photo?
I am curious if this is indeed a winter solstice sunset. Could this be a winter Moon rise or set?
1 Unless there are unique clouds right at the horizon, or image exposure adjustment, the brightness/color of the sun is unusually low.
2 The light on the clouds and and particularly on the end of the pipes (left pipe) is not consistant with the sun behind the subject.
3 Why is there is significantly more light on the left side of the central pipe, if the illumination is coming strait down the pipe?
4 If this picture is at sunset, on the winter solstice, the sun should be at the maximum SW extent of the array of pipes and in the photo it would appear in the NW quadrant. (Assumig North is to the right in the image)

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by BPCooper » Thu Dec 22, 2011 4:35 pm

On the photographer's own website, the same photo does not have a sun in it on the horizon through the tube.

I think it's a very nice photo, but the white sun as seen on APOD appears to have been drawn in. This photo was certainly taken after sunset at twilight. I would not mind it however the caption should probably indicate this.

Guest

Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by Guest » Thu Dec 22, 2011 5:49 pm

Some one ought to have to clean-up their mess. That abandoned concrete is an eyesore.

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by Case » Thu Dec 22, 2011 5:50 pm

TMart wrote:Does the photographer have any more details regarding lighting and time of photo?
There is some EXIF data in the .jpg, as e.g. Jeffrey's Exif viewer will show.
From it, we learn a.o. that the camera was a Nikon D700, the source image is 6,144 × 4,088 RAW, the exposure time is 1/50 sec, and the ISO was set to 400. The image date was 2010/12/27 17:37:41.

Edit: Stellarium confirms that this time (2010/12/27 17:37:41) is correct for the position of the Sun (screenshot).
Last edited by Case on Thu Dec 22, 2011 6:23 pm, edited 1 time in total.

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by Sandstone » Thu Dec 22, 2011 6:17 pm

Found it on Google Earth!

Latitude: 41 deg 18' 12.56" North
Longitude: 113 deg 51' 49.73" West

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by alter-ego » Thu Dec 22, 2011 8:43 pm

frankb4now wrote:I do believe this is a picture of a sunrise. If this is a sunset, it would suggest that North is to the right and somehow that would seem to impede the use of the star holes on the right side of the nearest tunnel.
Maybe the photo negative was reversed....and maybe I'm just plain wrong?
The view is looking southeast, and the image is not flipped.

Given the image is not flipped, there are only two possible views: Southeast (North to the left) or Northwest (North to the right). The terrain (Google Earth) and other Sun Tunnel pictures (http://www.flickriver.com/photos/tags/s ... teresting/ and http://www.flickr.com/photos/cbiggs/605 ... otostream/) corroborate the southeast view and that the image is not flipped. You can see the mini-cross set of holes (as well as others) to get your orientation. Sun illumination, terrain, and a nice celestial pole star-trail shot collectively reveal the southeast APOD viewing direction.
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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by zloq » Thu Dec 22, 2011 9:33 pm

I agree it sure looks like a morning shot, and north is to the left.

I'm more interested in the first sentence, though. It shows a common misconception about what the moment of solstice really is when it's calculated to the minute like that. Although solstice usually, and casually, refers to the moment when the sun is farthest north or south, in astronomical terms it is very different. The solstices and equinoxes aren't defined by solar declination - but by solar longitude along the ecliptic - and occur when the geocentric apparent sun is at 0, 90, 180, 270 degrees along the ecliptic. This means that it may be a few hours off from when the sun is actually farthest north or south. Normally this doesn't really matter - but when people specifically say that is the moment the sun is at its extreme position - or that defines astronomical solstice - it is incorrect.

This is described in Astronomical Algorithms by Meeus - but in this case the source of the computation is the U.S. Naval Observatory, and they spell out the definition succinctly here:

http://asa.usno.navy.mil/SecM/Glossary.html#s

zloq

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by biddie67 » Thu Dec 22, 2011 10:12 pm

I love things like this. I've designed a stained glass window with 3 vertical spots in where the light at noon on the 4 dates comes through and falls across the room on 3 different spots. Not perfectly accurate but fun for the grandkids to watch for .....

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by Beyond » Thu Dec 22, 2011 10:27 pm

biddie67 wrote:I love things like this. I've designed a stained glass window with 3 vertical spots in where the light at noon on the 4 dates comes through and falls across the room on 3 different spots. Not perfectly accurate but fun for the grandkids to watch for .....
Ah, Glass-Henge. 8-) Very 8-)
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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by corey » Thu Dec 22, 2011 10:45 pm

APOD editors should correct the description -- it is a sunrise not a sunset. I knew something was amiss, and I see others caught it too.

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by biddie67 » Fri Dec 23, 2011 12:49 am

Oops ~~ I meant "3 horizontal slots in a vertical line" above .....
Last edited by biddie67 on Fri Dec 23, 2011 10:08 am, edited 1 time in total.

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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by Beyond » Fri Dec 23, 2011 1:49 am

biddie67 wrote:Oops ~~ I meant 3 horizontal slots above .....
So It's Window-Henge instead of Glass-Henge. No problemento, It's still 8-) , very 8-)
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Re: APOD: Through a Sun Tunnel (2011 Dec 22)

Post by Mactavish » Fri Dec 23, 2011 2:18 am

Personally, I believe the photo is far more appealing than the “art”. But then, beauty lies in the eyes of the beholder.

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Why are misleading APODs permitted?

Post by mastrulo » Fri Dec 23, 2011 2:25 am

Der APOD,
Do any submissions get vetted for accuracy?
How can "Halting its steady march toward southern declinations and begining its annual journey north"
Referring to the Sun as obseved from the Earth be permitted to go public?

I am disappointed that it appears if the picture looks nice, doesn't matter what, how and why, lets post it.
Lately most APODs are just time lapse, looks nice and usually not much to do with Astronomy, OK the meteorites (if any lets after the fall), do apply to APOD, but for goodness sake, we have the absolutely marveouls mathematics and physics to get MESSENGER to be engaged (soon) in a stable and close orbit of Mercury, would that not be an excellent weeks' worth of APODs?
Instead we have because of the solstice the Earth orbit is now a South to North inclination?
How can this APOD be permitted? Why confuse the many that love Astronomy especially the youth, be told the Sun is now "Halting its steady march toward southern declinations and begining its annual journey north"??

Please, let's get back to reality, and some excellent material from NASA/ESA and many other sources, enough of time lapse and wonderful circular lines of the stars, perhaps ask those that love them to swing the camera on a string and we could have hundreds of 'scintillating' APODs.

Thank you.
mastrulo.
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