The Eratosthenes Challenge

A team (team A) of two groups in cities near the Earth’s equator performs a measurement of the local radius using the ‘classical Eratosthenes’ method but extended with clever techniques to reduce the measurement error as much as possible (see diagram below).

A team (team B) of two groups in cities at high latitude (north or south) performs a measurement of the local radius using the ‘classical Eratosthenes’ method but extended with clever techniques to reduce the measurement error as much as possible.

All teams should be located along the same longitude (as practical as possible). Corrections can be made for differences in longitude (i.e. time of measurement would be different and the method is still valid as long as the measurements are performed at the time of maximum Sun elevation)

The local radius measured by each team provides an estimate of the local meridional radius of curvature. From the ratio of the local radius from team A and team B (r = radius_A/radius_B) the eccentricity can be computed:

Factors that contribute to measurement errors and estimated magnitude of the errors:

(This sections is under construction)