The Moving Tropic of Capricorn

Abstract

Curiosity about the placing of the monument marking the Tropic of Capricorn on Botswana’s A1 road between Mahalapye and Gaborone reveals that: it is actually some 7 kilometre south of the correct position, that the line of the True Tropic is constantly moving; that it moves through a range of 267 kilometres and that Gaborone city misses inclusion in ‘the tropics’ by a bare 10 kilometres!