Method 1 There are several methods of doing this. One is to use a quadrant to measure the height of the Sun. (See graphic at right.) However, in the case of the Sun, you must not look through the straw at the Sun, Never look directly at the Sun with your eyes or any instrument, especially not a telescope or binoculars. To measure the height of the Sun with the quadrant, hold the quadrant such that the sunlight falls through the straw onto a neaby surface, then read the angle in degrees (using the weightes string indicator). This takes a bit of practice. Be sure to let the sunlight through the straw fall on a nearby surface (a few inches), or otherwise it may be difficult or impossible to see.
Again, be careful not to look through the straw at the Sun, and be sure that no one else does, either.
Method 2: Another possible method is the measure the length of the shadow of some known object. Then you can use trigonometry to determine the angle. If you wish to use this method, the basic idea of what you need to do is shown in the graphic to the right. You can devise your own set up, or click here for a suggestion: alternate setup graphic.) You can set this up in many different ways. For the shadow stick (called a "gnomon" -- see below), you will need a dowel or some other straight object. Strictly speaking, the taller the gnomon is, the better. However, it is difficult to assure that very tall gnomons are straight and upright, so don't use anything less than about 305 mm (roughly a foot). It is very important that it be straight, and standing perfectly upright. Even if it is leaning only just slightly, or is even slightly bent or irregular by just a few millimeters, your results will be significantly in error. Take your measurements in millimeters (mm). Most school rulers today have a metric scale with millimeters and centimeters. If you don't know how to measure in millimeters, the math help page has some information. (See "Measurements: Metric and Imperial")
The important thing is that you get an accurate measurement of the exact high of your shadow stick. The surface must be very flat, and the shadow stick must be straight and not tilted. (The shadow stick is technically known as a "gnomon", ("NO-mahn," pronounced like the answer some one from Jamaica might give if asked, "would you like a nice Hawaiian Punch?"). Please spell it correctly. It is not the same as a gnome (pronouced like the town in Alaska, Nome), which is the small, dwarf-like person featured on Travelocity commercials) Measure the gnomon's height from the point where the shadow begins, to the top directly above that point. The shadow is measured from the stick where the shadow begins to the end of the shadow. If the shadow stick is thick, do not add the thickness of the stick to the length of the shadow. I prefer that you at least try to do the trigonometry yourself (As trig goes, it is extremely simple.) However, if you just absolutely cannot do it, there is a calculator on the following page that will do it for you: ShadowCalc.
Once you have the shadow length, you can calculate the angle of the Sun with trigonometry using the shadow length and gnomon height: click here. Remember that you need to make 3 measurements and find the angle values for each measurement. You will then average the three angles for your final value. Your data table, which you must show me, should look something like this:
2/20 11:58 24 in 23 in 46.2 deg
2/20 11:59 24 in 22 in 47.5 deg
2/20 12:02 24 in 25 in 43.8 deg
AVERAGE: 45.83 deg
Remember that this is just an example, and the data is not real.
Method 3: I'm not going to give you a method three, but you can devise one of your own as long as you give me a complete and accurate description of what you did to make the measurements. Remember that you should never look directly at the Sun.
Once you have your averaged angle,GO BACK to the first page and complete the activity.
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