images

The Moon and sixty - Artist view

by

Space Channel/Novapix

Reference

a-cad98-00001

Date

2008-04-08

Sixty, not ten, was the basis of Sumerian math. The Sumerian calendar, the farming 'tool-kit', was based on the phases of the Moon; 12 x 29.5 days. This produced a year equal to 360 days; a reasonable approximation, but not accurate over time. Every so many years an extra month had to be added, and an incredibly complex math system was used to make the adjustment.