This project is funded by International Astronomical Union (IAU) is the the Office of Astronomy for Development (OAD) in partnership with the South African National Research Foundation.)

Using only the sunlight striking the Earth and a wooden dowel, students can measure the circumference of the earth. Eratosthenes did it over 2,000 years ago. In Cosmos, Carl Sagan shared the process by which Eratosthenes measured the angle of the shadow cast at local noon when sunlight strikes a stick positioned perpendicular to the ground. By comparing his measurement to another made a distance away, Eratosthenes was able to calculate the circumference of the earth.

This project meets standards for Math, Science, Reading and Geography.

Students receive buttons for each activity.