View Full Version : Winter Solstice Day. Here's your Analemma.
Astronomy picture of the day. An Analemma.
http://antwrp.gsfc.nasa.gov/apod/ap020709.html
Take heart. It's all uphill from here. :D
Great photo, I learned something new today ! :)
Very nice picture and info. New to me as well. Now that I learned something new today, does that mean I don't have to go shopping with the wife?:sun
Yes, I think you have some points in there somewhere, cry 'brain ache' and see if you can manage to get out of it :)
I knew that just not the name of it. I can see it happen in my own yard all you got to do stand same place ever day pick a tree to sight it.It start at top go down toward bottom then back up. Or start at bottom and go up.
Jan LiteShoe
12-22-2008, 12:52
Cool pic!
Happy First Day of Winter everyone.
We walked through the piney woods to an upper meadow last night at dusk to catch the dying of the light on the shortest day. Just one last cloud painted pinkish on the bottom, and it was gone. Very peaceful end of the light (and best holiday celebration yet).
Today ... SUNNY! It came back! Rebirth!
I love when that happens.
;-)
sheepdog
12-22-2008, 12:58
Cool picture. I live near a lake with an east view. You can really see the differences in the sunrises. In the summer the sun is farther north when it comes up. It steadily works its way south as winter progresses. Now it should start heading north again.
FritztheCat
12-22-2008, 13:16
Cool photo. The wife and I can always tell the sun is higher or lower depending on the time of year while sitting on the back porch. Neat to see a photo of the differences in one still.
Dances with Mice
12-22-2008, 13:31
Today is also one of four days of the year when sundials and watches keep the same time. The other four days are also shown on the analemma - the opposite end and the crossing point (remember that the sun passes through the crossing point twice).
TrippinBTM
12-22-2008, 15:22
that's cool! Question: which way does the sun move? Like, from the highest point, does it go down and left, or down and right?
it's all uphill from here, yes, but sadly, it's only going to get colder for a couple of months. I'm dreading January/February...
Already feels warmer. :p
Warmer than 10f, that is. :D
Blissful
12-22-2008, 15:40
That is really neat.
Sure am hoping 2009 is better than 2008 on several fronts. Sigh.
Rain Man
12-22-2008, 17:32
Already feels warmer. :p
Warmer than 10f, that is. :D
Nine degrees this morning here in Nashville. Brrrr.
Odd to think the days are now getting longer.
Rain:sunMan
.
Cool picture. I live near a lake with an east view. You can really see the differences in the sunrises. In the summer the sun is farther north when it comes up. It steadily works its way south as winter progresses. Now it should start heading north again.
Very noticeably way north. Some islands here in the bay to line up with.
8 seconds longer today! Yeehaw!
Wake me when it increases 3 minutes a day.
Nine degrees this morning here in Nashville. Brrrr.
Odd to think the days are now getting longer.Rain:sunMan.
I sympathize with you southern folk. Single digit and below temperatures are common here on the mid coast of Maine. I keep telling myself that I love the four seasons -- but I meant the global warming predicted four seasons -- you know when Maine was to become like Tennessee.
There seems to be a lapse in the warming plans. Portland, ME, which from where I live is pretty much 15 miles due East from Portland, had its deepest single snow storm in recorded history last night.
I think I heard snow there hit 14 or 15 inches. I wandered around a bit this afternoon with my aluminum yardstick -- purchased when I dreamed of doing some wall papering. Anyway, the depth on a handicap walkway I had built when my father-in-law lived with us -- which my wife shoveled, just minutes before the snow started -- measured 18 inches of new snow.
Elsewhere, around my two acres, snow depths totaled 20 inches -- but included some residue from a few days ago storm.
Whatever, this is an "old fashioned" start for the season. All of which the global warming scientists warned us might happen as we started messing with nature's atmosphere.
Weary
sheepdog
12-22-2008, 20:42
Whatever, this is an "old fashioned" start for the season. All of which the global warming scientists warned us might happen as we started messing with nature's atmosphere.
Weary
Such a nice thread. Why must we go there? Let's not.
garlic08
12-22-2008, 21:14
I think I've seen the analemma figure on some globes. Didn't know exactly what it was, or I'd forgotten. Thanks!
Such a nice thread. Why must we go there? Let's not.
The great deficiency of White Blaze is our continuing failure to be able to discuss rationally the truly important issues impacting our trail. But I'm also a realist. I won't. if you, and others, don't.
Weary
Jim Adams
12-23-2008, 01:39
Cool pic!
Happy First Day of Winter everyone.
We walked through the piney woods to an upper meadow last night at dusk to catch the dying of the light on the shortest day. Just one last cloud painted pinkish on the bottom, and it was gone. Very peaceful end of the light (and best holiday celebration yet).
Today ... SUNNY! It came back! Rebirth!
I love when that happens.
;-)
Oh, I am so jealous! I was at work and so busy that I forgot the date and happenings.:mad:
Nice photo...I learned also.
geek
TrippinBTM
12-23-2008, 07:30
I think I've seen the analemma figure on some globes. Didn't know exactly what it was, or I'd forgotten. Thanks!
I'd seen the symbol, but never visualized what it would look like with the real sun by making a collage. And I still don't quite understand why it's a figure eight, instead of just a linear path...
Dances with Mice
12-23-2008, 07:34
that's cool! Question: which way does the sun move? Like, from the highest point, does it go down and left, or down and right? Here's a diagram (http://www.analemma.com/Graphics/summation/summationEffect/AnalemmaCurve.GIF).
generoll
12-23-2008, 08:40
good depiction, DWM. I studied celestial navigation once upon a time and I remember something called "The Equation of Time" which was probably a long winded explanation for what your diagram shows. I never worried about it too much since the equation is already figured into the data in the almanac. This is the clearest explanation I ever seen. I can actually understand the how, even if the why is still a bit fuzzy.
garlic08
12-23-2008, 09:26
I'd seen the symbol, but never visualized what it would look like with the real sun by making a collage. And I still don't quite understand why it's a figure eight, instead of just a linear path...
From what I understand, it's the 'wobble' of the earth's axis. That might explain a lot of other things, too.:rolleyes:
Dances with Mice
12-23-2008, 10:07
good depiction, DWM. I studied celestial navigation once upon a time and I remember something called "The Equation of Time" which was probably a long winded explanation for what your diagram shows. I never worried about it too much since the equation is already figured into the data in the almanac. This is the clearest explanation I ever seen. I can actually understand the how, even if the why is still a bit fuzzy.About a decade ago I got too interested in sundials, even made a spreadsheet that would design one corrected for the latitude and longitude of any site then I built a temporary mock-up of one to test in my yard before I built a more permanent one. So you know what that means? Yeah, the temporary one is still out in the yard.
The equation and time and the analemma both show the results of two effects: the tilt of the earth relative to the sun, which causes the figure 8 shape and the earth's eccentric, oval'ish orbit which causes it to move at different speeds during the year. Add all that together and you get the offset figure-8 shaped analemma.
If you ever visit Longwood Gardens in Pennsylvania you can see an incredibly accurate sundial. Mr. Pierre DuPont (that guy must have had a buck or two to rub together, y'know?) hired a full time astronomer who spent several years designing it. It has a large analemma inscribed in a giant concrete pad with months and days marked on it. When a large wrought-iron lamp-post looking pole is moved directly over the date, its shadow falls on a huge metal dial laid around the pad. It is accurate to the minute but, rather obviously, doesn't correct for daylight savings time.
COOL!!! This photo and accomanying info have made my day!
Frau
Dances with Mice
12-23-2008, 10:24
I'd seen the symbol, but never visualized what it would look like with the real sun by making a collage. And I still don't quite understand why it's a figure eight, instead of just a linear path...This movie link (http://www.analemma.com/Graphics/tilt/tiltEffect/TradTiltEffect/Alt.mov), if it works, explains that. It's exaggerated, but it shows the sun's annual path across the sky. It fixes the earth as the center of the universe then animates the sun's tilted rotation around it.
Sundials don't really care who rotates around what, they worked well way before those troublemakers Copernicus and Gallelio were born.
Blue Jay
12-23-2008, 10:45
The great deficiency of White Blaze is our continuing failure to be able to discuss rationally the truly important issues impacting our trail.
I could not agree with you more, however this is a nice little holiday thread. I spent a few precious moments yesterday on top of my favorite little mountain near my home. It's only 1500 feet but it felt and looked like my illusion of Everest. The wind was sooo strong that even though my eyes were the only thing uncovered (should have brought my ski goggles), it felt like they would freeze in my head. There are 2 little uphill valleys (colls) that had the snow exploding upward like fountains. Bright sunlight even though most of the ski was dark blue/blue/black I watched as long as I could then had to ski down. On an ordinary day in a place I've been a thousand times you don't expect moments you wiill remember forever.
Mrs Baggins
12-23-2008, 11:28
Astronomy picture of the day. An Analemma.
http://antwrp.gsfc.nasa.gov/apod/ap020709.html
Take heart. It's all uphill from here. :D
That's beautiful! As a Winter Solstice baby it has some meaning to me. :sun The Celts did not celebrate the Solstice as the on-set of Winter, they celebrated because they saw it as the start of Spring - from that day forward the days would get longer and there was the promise of new growth again. They saw the days following harvests to the Solstice as "winter" - more darkness, growing cold, everything "dead." When you think of it that way it can change your whole outlook on winter!