eldon Posted February 21, 2012 Share Posted February 21, 2012 Going at a slight tangent, but responding to the thread's title, there is a simple way of finding out true North. Look on the web for the Equation of Time, and you will find that on four days of the year, the Sun time coincides with the Clock time - April 15, June 12, September 1 and December 24. On these days, the sun is South (or North) at local noon, which is the time that the sun is highest in the heavens. So wait until the appointed hour, hang a plumb line or set a vertical pole, and the shadow will be exactly North (South) Quote Link to comment Share on other sites More sharing options...
SLW210 Posted February 21, 2012 Share Posted February 21, 2012 True North and magnetic North only line up with the geographic North and South poles, if you happen to be on a line that intersects all three points, with your compass in your hand. This alignment will only last long enough for you to perceive it, than it moves on. You can get the compass to point to both North Poles by being on a line that intersects both poles, but you need to keep moving. There is no point anywhere on earth that you can truly state that magnetic North and true North are in the same direction from where you are standing, ever. By the time you go "Yaaahooo, I found it", it will be a few centemeters away and moving further on its merry journey. Not quite true, in South Florida the Agonic Line (where True North and Magnetic North are the same) has moved around 500 or 600 miles in the last 30-40 years, so 12.5 miles per year is 3.96109558 × 10-7 miles per second or 0.00142599441 miles per hour or 12.5 miles = 66000 ft = 0.025 inches per second (0.064cm per second). In other locations it varies by much less and in some by much more, see the attached. Quote Link to comment Share on other sites More sharing options...
Dana W Posted February 21, 2012 Share Posted February 21, 2012 Not quite true, in South Florida the Agonic Line (where True North and Magnetic North are the same) has moved around 500 or 600 miles in the last 30-40 years, so 12.5 miles per year is 3.96109558 × 10-7 miles per second or 0.00142599441 miles per hour or 12.5 miles = 66000 ft = 0.025 inches per second (0.064cm per second). In other locations it varies by much less and in some by much more, see the attached. Well, OK if you wanna stop and do the math and all, but it's still movin. (change "a few centemeters" to "a short distance") The mag pole itself has been timed at anywhere from 12 to 37 miles per year. (My wife does that too. If I incorrectly assume about anything with numbers in it, she'll break out the scientific calculator.) Quote Link to comment Share on other sites More sharing options...
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