North - Roles of East and West As Inherently Subsidiary Directions

Roles of East and West As Inherently Subsidiary Directions

While the choice of north over south as prime direction reflects quite arbitrary historical factors, east and west are not nearly as natural alternatives as first glance might suggest. Their folk definitions are, respectively, "where the sun rises" and "where it sets". Except on the Equator, however, these definitions, taken together, would imply that

• east and west would not be 180 degrees apart, but instead would differ from that by up to twice the degrees of latitude of the location in question, and
• they would each move slightly from day to day and, in the temperate zones, markedly over the course of the year.

Reasonably accurate folk astronomy, such as is usually attributed to Stone Age peoples or later Celts, would arrive at east and west by noting the directions of rising and setting (preferably more than once each) and choosing as prime direction one of the two mutually opposite directions that lie halfway between those two. The true folk-astronomical definitions of east and west are "the directions, a right angle from the prime direction, that are closest to the rising and setting, respectively, of the sun (or moon).