Size of the Earth

Project for Elementary Astronomy

It is relatively easy to measure the size of the Earth using simple tools at your disposal: straws, string, brains, and feet. In this activity you will follow in the footsteps of Eratosthenes, a Greek astronomer of the third century BC. Eratosthenes' method involved observations of the Sun on a specific day (the summer solstice); you will instead use the fixed position of the star Polaris.

This activity can be done only if you are going to be traveling 150 miles or more due north or south this semester--the farther the better. Neither Price nor Pocatello is quite far enough, but Richfield or Rexburg is adequate. This is a great project if you are planning such a trip already. You'll also need to have clear weather at night when at your destination (and at home).

To conduct this observing project, follow this procedure:

A cousin to the astrolabe that you can build in your kitchen.

To complete the project, include the following in your analysis: