Tape this silhouette onto your manila folder sheet and cut out this
Make a tiny hole at the index point (marked by an "X"), push
the end of a 7-inch piece of string through the hole and tape that end to the backside of
the cardboard. Attach a paper clip to serve as a weight at the other end of the
string that falls over the degree markings on the front of your astrolabe.
Fold the cardboard along the dashed line as indicated on the diagram so that
the sides with the triangular notch form a right angle with the face of the
astrolabe. Make sure the sides are still at a right angle at night when you use
Take your astrolabe home to use at night. Using a star map, locate the Big
Dipper, which will point you to the star Polaris. Face Polaris and raise your
astrolabe until you can sight Polaris through both notches. Make sure that the
paper clip and string are hanging straight down (i.e., do not tilt the
cardboard as you sight on Polaris; the astrolabe must be perpendicular to the
When you can see Polaris throught both notches, press the string against the
cardboard and record the angle at which the string crosses the scale. This
angle is the altitude of Polaris, which is also your latitude value.