Analemma (APOD 17 June 2007)

Comments and questions about the APOD on the main view screen.
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Joined: Sun Jun 17, 2007 11:02 am

Analemma (APOD 17 June 2007)

Post by canuck » Sun Jun 17, 2007 11:14 am

Would the sun form the same figure eight pattern if the photo was taken at celestial noon for that location? It is my understanding that at celestial noon the sun is due south and is at its highest point in sky. The sun is at its highest point at summer solstice and lowest at winter solstice. So if the photo was taken at local celestial noon the pattern would be linear and provide an indication of due south?

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Joined: Sun Jun 17, 2007 4:02 pm


Post by emyk5164 » Sun Jun 17, 2007 4:08 pm

It seems that all analemmae (sp?) have a central convergence point, where it seems the sun crosses itself. Is that point occurring at the vernal and autumnal equinox?

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Post by rigelan » Sun Jun 17, 2007 9:35 pm

Solar noon is defined by the highest position of the sun on any particular day.

But whether that is due south every day of the year (for those of us north of the tropic of cancer of course) I am not sure. I am guessing it could form the analemma too. But my instinct says that it probably is always due south.

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Post by makc » Mon Jun 18, 2007 8:24 am

that's nice how this apod links to digg thread of its older brother instead of linking to it directly... btw, digg it.

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Location: USA

Post by AZJames » Wed Jun 20, 2007 7:55 am

I've always wondered why analemmae seem to have about the same angle to the horizon. Does it have anything to do with the latitude of the observer?

Ok. On reflection, I can see that my question was stupid. :oops:

Obviously, an observer in Anchorage, Alaska (for example) would observe a virtually horizonal analemma.