Prelude Why I Developed this Website by Ihor Charischak
The Story The Librarian who Measured the Earth - Details of how Eratosthenes (275-194 BC) the chief librarian of the finest library of his time made his remarkable measurement.
Some ideas for teaching this unit Strategies for teaching and learning this "unit".
Doing the measurements Helpful suggestions for doing the project.
you need is the one formed by the meter stick and the sun's rays
acute angle opposite the base angle of the triangle formed). In the
its the angle that is covered by the protractor.
An Example of measuring the
circumference from two locations on the earth.
Using Trigonometry An introduction to the ideas used by Ken in his spreadsheet explanation below.
Using Spreadsheets Ken Cole's explanation from the 1997 project.
Some Useful ToolsDownload A Sketchpad Noon Day project. (requires GSP 4)
A Java Sketchpad model which lets you explore the angles formed by the sun's rays at Alexandria and Syene.
A Java Sketchpad model which lets you explore when there are shadows at both locations.
Finding your latitude and longitude
Another way to latitude and longitude is to use Google earth.
For downloading information go to http://earth.google.com/
Finding your distance between sites
Tools for finding Local Noon