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On December 21, 2012, I made an accidental, but startling, discovery as a result of initiating the installation of a small starter system for solar power. A brief chronology is below.
In 2011 I began researching the installation of a small solar system, primarily for lighting. In order to determine true south, I knew one low-tech way was to line up three stakes at exactly 12 noon on either winter solstice or summer solstice so that they make one shadow. I picked winter and did manage to align the three stakes at 12 noon with the sun's shadow from the first stake falling on the second, and the shadow of the second falling on the third stake, making for a straight line shadow, aligned with the three stakes. I did all of this, but was a day late, on the day after winter solstice. One day makes hardly any difference in where the shadow will lie, but being a purist, I decided to wait another year so that I could nudge stakes 2 and 3 into their proper positions, a few millimeters away, for a true winter solstice north-south line.
On December 21, 2012, a few minutes before 12 noon (synchronized by official time per internet clock) I went to my site planning to nudge stakes 2 and 3 a few millimeters into their proper positions. I was dumbfounded by what I saw. I had to scramble to find 3 new stakes because the sun was in a totally different orientation and I managed, in my 60-second time interval at exactly 12 noon, to pound 3 new stakes in the ground representing the north-south line for 2012, The 2011 and 2012 north-south lines make a big "X", intersecting each other, rather than aligning. Still in shock, I got a carpenter's square and tried to wedge it between the legs of the "X" without dislodging the stakes. Unbelievably, the angle looks to be around 45 degrees!
Now I do recall in 2011 when I first did this, I kept looking back up at the sun, then back, at the stakes, then muttering to myself that "south" seemed too far east, but this is what it is. I remember looking in the direction of where I thought south should be and wondering how I could be so far off. But the sun rules. The location in the sky where the sun appears to us on Earth is dependent on the tilt of the earth's axis of rotation as it travels around the sun, Earth's location in its path around the sun, as well as the location on Earth of the observer. The way I understand all of this tells me the Earth's axis of rotation between December 22, 2011 and December 21, 2012 changed considerably.
I researched the Chandler Wobble and do not believe that is the key to this anomaly. I suppose at this point my only advice to anyone contemplating installing a south-oriented solar system, is to forgo a permanent roof mount, and go with a pole mount in which the array can be re-oriented if necessary. For those with extra cash, a sun-tracking system would probably suffice, as one friend of ours uses one and he is very pleased with its sun-tracking capabilities. He even mentioned that on a very overcast, but very bright, day, the arrays will be pointing straight up.
Attached are pictures of my primitive stakes, as well as the carpenter's square. Remember in looking at these, I did not anticipate this little solar power endeavor would evolve into a science project, else I would have poured concrete for the first stakes, etc., etc. I am hoping someone else will follow suit, and perform his/her own little experiments. If you do, and are not surrounded by trees on the north, a more accurate way to determine the north-south line is to align the stakes at night with Polaris, the North Star. The drawback to my method is that each time zone is hundreds of miles wide and everyone in the same time zone is not at the same exact location. Using a compass is not a good way to determine the north-south line because of iron ore in nearby deposits, as well as watches, batteries, belt buckles, etc. But if trees on the north are an issue, my method works very well. If you select one method, stick with that same one with all observations. Better yet, do both for comparison.
One final note is that my original stakes from 2011 had never been moved or manhandled during the year, as I observed them on almost a daily basis and am very familiar with their surroundings, etc. Also, I should mention that I have done, and am doing, a little more research reserved for a future article and am planning to again check north-south lines on both summer and winter solstice this year, assuming sunny days will accommodate.
If Earth's axis of rotation is changing, think of the implications for food production, solar energy production, and who knows what else? Ponder this food for thought.