Tuesday, December 22, 2009

An Analemma Idea

Stuart, Florida

We moved from Vero to Stuart, just for a change in scenery. More later.

Today, I want to talk about a great idea I just had inspired by the picture below.


I got the picture from APOD. It shows an analemma. I've published several pictures of analemmas before. I just love their beauty; what they reveal about our natural environment; and the artistry and skill of the photographers who make them.

In case you don't know, an analemma is made of multiple exposure pictures of the sun, all taken from the same place at the same time of day throughout a whole year. The proportions of the figure-8 depend on the observer's latitude. For example, at the Arctic circle, the bottom of the analemma would kiss the horizon on the winter solstice. The picture includes 32 such exposures including one which shows the sun in total eclipse. What skill and artistry. Kudos to Cenk E. Tezel and Tunç Tezel, who made it.

Anyhow, my idea is to make an analemma of the sun as seen from the decks of Tarwathie. Since we move between 45 north and 25 north as the year goes on, the shape of a Tarwathielemma would be a distorted morph between a 45 analemma and 25 analemma, with further distortions caused by change in longitude. The result would be unique to our travels. Wow would that be cool.

Before actually making it, what should I expect? Well, since we follow the sun north and south in search of temperate weather, my first guest is that our analemma would be squashed to nearly a single point in the sky. If we did a perfect job of following the sun, the sun's position at the same hour of the days would be fixed during the year. Our position on the globe however, traced through the year, would look like an analemma. How very very cool.

So, how could I make a Tarwathielemma from the deck of a rolling sailboat? Well, given a million dollars worth of electronics, instruments, servos, cameras and computers, I could make it directly. It would be an exceedingly difficult project. But wait; I could make a simulated one using my favorite program Stellarium. All I need is a history of our latitude and longitude from our log book, Stellarium, and then a little work with a program like Photoshop. I bet I could do it in 8-10 hours of computer work. The result would be totally artificial and it would lack the beauty of real pictures and a static landscape. Still, it sounds like a really fun challenge. I'll give it a try and post the result on this blog when done.

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