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:
Date Time
Gnomon Shadow
Angle
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.
(Copyright 2008 by Final Copy, Inc. All rights reserved.
Contact
for permissions.)
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.