How to Find Latitude

Make an astrolabe. Lay the protractor on the piece of paper and draw a quarter circle (an 'arc') using the protractor. Draw two lines toward the center of the circle from the ends of your arc so that you end up with the outline of a quarter circle (or 'quadrant'). Along the arc, mark in the angles from 0 degrees to 90 degrees in 10 degree increments using the protractor. Draw small lines for every ten degrees. You can mark all 90 degrees if you want for greater accuracy. Cut out the paper quadrant and glue it to a piece of cardboard cut the same size. Punch a small hole through the corner opposite the arc. Tape the straw to the edge of the astrolabe so that one end is near the 90 degrees mark and the other end near the string hole. Tie one end of the string through the hole. Tie the weight on the other end of the string.

Find Polaris. Polaris is the bright star also know as the North Star that sits in the sky above the North Pole. Use a star chart to find the Big Dipper and Cassiopeia. Follow the arrows on the star chart from the Big Dipper and Cassiopeia to locate Polaris.

Find Polaris by looking through or down the length of the straw; the arc side of of the astrolabe should point toward the ground. When you find Polaris, the string will hang next to a degree mark. You can hold the string in place to find the degree or have a friend measure the angle the device indicates. Record the measure. This recorded angle degree is called the altitude of Polaris.

Equate the altitude of Polaris to your degrees of latitude--the two are the same. With a simple astrolabe, you have used astronomy to find your latitudinal position on Earth.