A long range sighting and terrestrial refraction

Abstract

The sighting of a distant island fixed on a digital image allowed us to measure the refraction coefficient and probe terrestrial refraction models. The measurement has been proposed to first-year students of Physics on behalf of the geometrical optics course held at Pisa University. The argument is inspired by a passage from Snell’s seminal treatise on geodesy raising the issue of terrestrial refraction, and it is developed in learning by doing context in which students are solicited to (re)construct a theory and compare measurements with simulation.