NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
"Sun Slow Day" is coming...
From: Frank Reed
Date: 2009 Feb 9, 00:11 -0800
From: Frank Reed
Date: 2009 Feb 9, 00:11 -0800
I'm starting a new holiday. It's called "Sun Slow Day". It's coming up in the next few days. "Sun Slow Day" is the day during the year when the Sun is latest getting to the meridian. It will reach the meridian about 14 minutes and 15 seconds after local mean noon. In terms of the analemma, it's the spot that is at the right edge of the larger lower lobe of that "figure-eight" shape. On a graph of the Equation of Time, it's the deep minimum that occurs in northern hemisphere winter. I propose that "Sun Slow Day" should be properly celebrated by fourteen minutes and fifteen seconds of procrastination. If you're trying to explain to explain to people lacking in astronomical knowledge why they should care about "Sun Slow Day", you can tell them that this is the day in the year when the maximum ultraviolet exposure occurs latest in the afternoon (though of course days when the Sun is at higher altitude inevitably have higher total exposure). So if you're looking for a perfect tan in some part of the world where it's warm enough for that (that just might be Chicago in a couple of days --we're having a heat wave to make up for our Siberian January), then you should lay out for a time centered around 12:14 local mean time. Time zone corrections are much more important, but we can deal with that in the next lesson... :-) So now here's a serious question, which I think would be a good challenge for the calculating folks of NavList. For the year 2009, what is the exact moment when the Sun is slowest? That is, on what day and at what hour of GMT does the Equation of Time reach its minimum value for the year? And how much does this change from year to year? And an easier question, what is that minimum value? -FER --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---