Solar geometry and other apps

Even though we haven't got to the shortest day of the year yet, yesterday was the earliest sunset. The evenings get later from today on, although the sunrise will keep getting later too for more than another fortnight, so the days are still shortening.

I was thinking -- if the sunrise keeps getting later, does the sun keep rising further and further to the south? So what about Newgrange, then? If you can't get in to see the spectacle on the solstice, can you meet the sun "on the way back" a week or so later? No, as it turns out. The solstice is the day of the most southerly azimuth of sunrise.

If you're like me, the answer is not necessarily intuitive! Not for the first time, I remarked on how bloody complicated solar geometry can be, given that it's just one ball bearing whizzing round another. But I found this fab applet on the University of Nebraska-Lincoln's website:

http://astro.unl.edu/naap/motion3/animations/sunmotions.html

So neat! I think the little stick figure's shadow is a lovely touch. And it turns out there's a whole collection of astronomy related simulation applets. I haven't looked at them all, but if they're as good as the solar geometry one, they will be fantastic visualisations, not just for novices.

http://astro.unl.edu/naap/