Wednesday, July 6, 2011

How To Use Shadows & The Sun As A Compass To Find Your Direction

If you’re not familiar with celestial navigation or if you’re trying to find your direction during the day, then the sun itself can be one of the most useful tools you never knew you had. The sun rises from the Eastern hemisphere and sets in the Western hemisphere. If you are within the Northern hemisphere then the sun will be due South at noon and if you are within the Southern hemisphere then it will be due North. The actual hemispheres themselves can be indicated by the direction a shadow moves. Shadows move counter clockwise in the Southern Hemisphere and clockwise in the Northern Hemisphere. Below are some of the most commonly used methods of using the sun and shadows to determine direction:

Setting Up For The Shadow Stick Method – First find a straight stick that is roughly about 3 feet long and about ½ to 1 ½ inches thick. Then locate a smooth area out in the sun that will not be affected by the shadows of other surrounding objects. I personally always try to locate a spot offering the highest elevation so that you have a great observation point to assign objects within your horizon a direction or angle of departure. Once a location is found, then drive the stick into the ground enough to ensure that it is secure and that it will not be affected by the wind or elements. If it is a rocky or sandy area, then you can drive the stick as far down as possible and then secure it with some type of cordage to help keep it upright and straight. It is critical that the stick remain in the same spot in order to provide accurate measurements. Also, try to position the stick as vertically level as possible. The easiest way to check is to make a quick homemade plumbing bob by tying a rock to some cordage and hanging it by hand close to the stick to compare them, adjust if needed. Now there are two main ways to use a shadow stick, so we will discuss both of them below.
Method A – In the morning sometime before 10 A.M., mark the spot that the tip of the sticks shadow meets the ground by either marking the soil or placing a rock on top of it. This marking will represent your West heading. Now using a piece of string or other cordage, measure the distance from this point to the base of the stick. Now use this same distance to draw an arch or circle around the stick. The shadow from the stick will start to shrink throughout the day close to noon and then begin to extend once again later in the afternoon. At some point in the afternoon the tip of the sticks shadow will intersect the arch you drew earlier. Mark this spot in the afternoon arch as your East heading. Now connect both marks and you will have your line of direction pointing from East to West. You can then draw your North and South lines perpendicular to the East and West line markings. It is also helpful to make a semi-permanent structure to depict your directions afterward if you are not departing right away so that a flash rain, snow, high winds, or any other of the elements do not disturb your findings.
Method B – This method is much quicker but is not quite as accurate. The setup is identical as Method A but only requires that you make two marks within approximately 15 minutes of each other. This method is best used before 10 A.M. and after 2 P.M.. Begin by making one mark where the tip of the sticks shadow meets the ground, this marking will represent your West heading. Then wait approximately 15 minutes and make another mark where the sticks shadow meets the ground, this marking will represent your East heading. Now connect the two marks for your East and West line of direction. You can then draw your North and South lines perpendicular to the East and West markings. Again, it is also helpful to make a semi-permanent structure to depict your directions afterward if you are not departing right away so that a flash rain, snow, high winds, or any other of the elements disturb your findings.

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