Making an Astrolabe

This instructable is about making an astrolabe, I'm making this 'ible for the space challenge competition. So about astrolabes: the astrolabe was invented in Greece either by Hipparchus, a 2nd century B.C. astronomer, or Apollonius of Perga, a 3rd century B.C. mathematician. For many centuries, it was used by both astronomers and navigators, and especially by the 15th century explorers who used it to determine latitude, longitude, and time of day. It is also used to measure the altitude of an object and detect changes in the position of the sun.

These are the things that you will need.

Tools:
1- hole poking thing
1- pair of scissors
1- roll of tape or glue

Parts:
1- astrolabe template thing*
1- piece of cardboard bigger than template
1- straw
1- long piece of thread
1- washer

*You will be cutting out the template thing to cut and glue it on the cardboard.

Go to this link and print out the angle thing http://cse.ssl.berkeley.edu/AtHomeAstronomy/act07_astrolabe.html . Make sure that you size it right because you don't want it to be to big or to small. Then cut it out and glue it on a stiff piece of paper or onto cardboard. Then cut the cardboard to to make it match exactly the angle thing. Then poke a hole where the little dot is on the right angle of the angle thing. Make sure that you cut out the little notches where it has the angle measures. 

Now you must attach the straw to the flat edge where it says "attach straw here" by using tape or glue. Then get your piece of thread and cut it so it is a couple inches bigger than the other flat edge, then tie one end through the little hole on the angle thing and the other end to the washer. Congratulations, you have made an astrolabe. It should look a little like the picture below.

To become familiar with how an astrolabe works, practice measuring the altitude (angular height) of trees or buildings. To make a proper measurement, look at the top of the object through the straw. The point where the string crosses the scale is the proper measurement. To find your latitude, find polaris, then measure the angle, then subtract the angle by 90. There is a way to find your latitude in the day, but I don't know how to do it. I hope you enjoyed this 'ible on making a simple astronomer's tool.