Hon Brendan Nelson and students at St Ives High School launch Science Week

Pictured are the Hon Dr Brendan Nelson and students from St Ives High School launching National Science Week with the Eratosthenes Experiment.

The Eratosthenes Project, a recreation of a famous ancient experiment to measure the circumference of the Earth ran during National Science Week - with the help of several thousand school students. The original experiment took place more than 2200 years ago when astronomer-poet Eratosthenes (air-ah-TOS-thin-ees) attempted to calculate the size of the Earth through measurement. Believed to have been the first scientist to attempt such a feat, Eratosthenes correctly assumed that the Sun is sufficiently far away from the Earth that you can consider its rays to be parallel when they reach the Earth.

During National Science Week, 103 schools across Australia measured the elevation of the sun at local noon. By combining the data from pairs of schools at different latitudes, the students will be able to calculate the diameter of the earth. The schools had to determine local noon and find ways of measuring the elevation of the sun on the same day as their partner school.

The next phase of the project involves analysing the data to determine the diameter of the earth and also the reliability of the estimate. The reliability or uncertainty is very important because it is the criterion on which the results will be judged to win the $1000 prize for each school of the winning pair. Schools separated by the largest latitude difference have a natural advantage in getting the best result because they have the biggest angular range to use in their analysis, but they have no such advantage in estimating the uncertainties in their result.

This project was organised and sponsored by the Australian Institute of Physics & RMIT University and the Department of Education, Science and Training as part of the Einstein International Year of Physics.

Further details are available on the RMIT Scienceweek web site www.rmit.edu.au/scienceweek. RMIT Applied Physics will be publishing the results of the project on September 26.