Celestial Navigation
The (nowadays) somewhat arcane method of determining your location on the surface of the earth, based on star shots.
Star shots are nothing more that determining the angle above the horizon of a given star or planet. The star shot is taken with an instrument called a sextant (pictured at left). The one pictured here is sold by Celestaire, Inc..
By taking two or more shots and performing some simple arithmetic on the time of the shots and the angle of the heavenly bodies, it is possible to determine your exact location on earth.
I've always been interested in just how this was accomplished, so recently, I did something about it, and took a short course on the subject. Here, I've gathered some links together that relate to the topic, and where appropriate, I've added some commentary of my own.