posted
I'm reading a book called Sundials: Their Theory and Construction by Albert E. Waugh. Dover 1972.
What's fascinating is that while I started this reading because I was thinking I might want to build a sundial as a project, I've ended up being fascinated by what sundials can teach us about the planet Earth, about Geography and Geometry and even a bit of Trigonometry.
I'm stunned. There are things I never knew about Earth latitudes that suddenly become abundantly clear when thinking about using a shadow to note the passage of time.
The angle of the sun and seasonal changes in apparent "noon" are also fascinating subjects.
I'm seriously wondering why I wasn't taught geometry by way of learning sundial construction. I swear it would've all made perfect sense to me if it'd been approached from this practical standpoint. And, moreover, I would've been learning some great stuff about Earth, the solar system and the stars too.
Anyway, this book is an old one, but I found it in a used bookstore for under $5.00. I'm sure it must be out of print, but I bet there must be others out there that are just as good.
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posted
If it taught about calenders you may be able to answer this triva question, one of my favorites: What day of the year is the Earth closest to the sun?
There is a great sundial program reviewed in a recent Sky and Telescope issue, like Sept. or Oct. There may be a share-ware version.
Have you seen the PBS special on Choco Canyon? Very cool documentary about Native Americans in the southwest who had a very sophisticated, knowledge of the sun, moon and earth cycles. They used incredibly advanced observational and surveying techniques in their building of the Choco Canyon complex, a large group of buildings spread over miles that align with each other and the sun and moon, including a unique system of using lunar maxima and minima rising and setting to align some of their buildings,integrated with other buildings which were aligned with the sun
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I have heard of the Choco Canyon site, but didn't really know much about it.
There's a bit in there about calendars. And yes, we're closest to the Sun on Dec. 25th if I recall correctly. And that's one of the days where apparent noon and actual noon are the same time every year at every latitude. The other time is where we are at our furthest from the sun, I guess.
Was that the right answer?
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posted
Hmm...unless it's moved since 1972, the date on which apparent noon and actual noon coincide is Dec 25th. That much is true. I guess that doesn't actually happen on the solstice though.
Or this book is wrong and I can't trust a thing the guy says.
Or I'm misremembering what it was that happens on Dec 25th in terms of sundials and I should go look it up.
It would seem to make sense that this would happen ON the solstice, but I swear the book said it happens on the 25th.
What do I know? My sum total of knowledge on the subject comes from the first 4 chapters of this book.
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posted
I'm not sure what day the noons correspond. But it's not the same as the closest approach to the sun, perihelion. I'm researching my question--so far I have 3 dates. Mine was wrong. I'm not sure if News of the weird or NASA is a better source--a feng shui/shamanism webpage is clearly wrong.
posted
Bob, it's surprisingly difficult to pin the perihelion date down. NASA says Jan. 4th, news of the weird says Jan 3rd. I thought it was Jan. 1st, I think that was the original intent of the calender. Oh, well, I've been meaning to research that for years. But now I'm researched out. I did learn some new words:
quote: Actually "day" here means a day and a night. Calendricists have a word for a day and a night, namely, "nychthemeron". Generally when calendricists use the term "days" they are talking of nychthemerons.
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Kwea, what time of year will you be visiting Arizona? Summer is NOT the best time to visit. It's been said the the devil visited Arizona one summer, but went home because it was too hot here. I'm just giving you a heads up.
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Kwea, I badly want to go there too. It is a very mysterious site. There are no sundials per se--the buildings themselves are aligned with sun and moon cycles, along with a sun spiral that the sun and moon cast shadows and light on through windows. The moon cycles are on a 18 year period, so it would have taken generations of careful observations to notice them. I got all this from a video, The Mystery of Chaco Canyon. I've seen it twice on PBS, it's very good. It is narrated by Robert Redford and won several awards.
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There used to be a world-class clock museum in Rockford, Illinois. In 1999 some was moved to the Smithsonian and some were on display at theChicago Museum of Science and Industry. The exhibition closed early this year, and Sotheby's is auctioning off pieces.
You would have loved the sundials, Bob.
[ November 21, 2004, 10:38 AM: Message edited by: Sara Sasse ]
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There is one show on the Science Channel that mentions it, though, and has some video. I'm always excited when I see that it's on (which, this being the science channel, is once a month or so).
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I plan on going whenever my parents retire, summer or not. They are moving to Casa Grande next year sometime, and I will probably go ut to help them settle in.
I will post the dates here once I know more...JeniK and I will probably go for a full well, adn at the least visit the Grand Canyon area.
posted
ooohhhh! The Chaco Canyon video was available at my local library - I put it on hold. It sounds fascinating.
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Avid, I just skimmed those pages, I'll have to look for that.
Bob, sorry to have derailed your thread, I didn't mean to. In recompense, I found that sundial share ware program, called shadows: http://perso.wanadoo.fr/blateyron/sundials/gb/ I haven't tried it, but the review in Sky and Telescope made it seem pretty cool.
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I'm going to try to find that book, or something similar. Thanks.
I've used stonehenge to teach various aspects of earth science, especially the tropics, the arctic circles, solstices (latitude and longitude then come naturally), and historical calendars. I've been toying with the idea of building a stonehenge of some sort with my students when I get the chance.
I also bought a sextant to teach trig and stuff, but I haven't had the opportunity to use it yet.
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Hey, if anyone finds an extra copy of that book and wants to mail it to me, I'd sure appreciate it. (That's not too subtle, is it?)
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Skimming through here as I just returned from the best four days of the year, but I did my Master's project on an integrated unit about sundials. If anyone is interested, I can dig it up. it would be a great hopme school project.
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Ic, It was aimed at sixth grade, but would be fine for older kids.
A woman I worked with also did a cool project with fifth graders, which I thought was pretty over their head mathematically. They measure the earth like Eratostanes did, using a group of kids in Maryland and a group in Mass. That project might be on the Internet if you goole Liliana Klass.
I used Marilyn Burns' lesson with hinged mirrors. Heck, I have to see if i can find it. I did it on Mac, and lost the disc, but I could give you the bare bones. It could be adapted for any age group for sure, and works so nicely with myths of the sky.
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![[Grumble]](graemlins/grumble.gif)
I'm not sure if News of the weird or NASA is a better source--a feng shui/shamanism webpage is clearly wrong.![[Wink]](wink.gif)
I'm just giving you a heads up.![[Frown]](frown.gif)
![[Big Grin]](biggrin.gif)
(That's not too subtle, is it?)
