The Equinox Shadow Stick

We are all aware that the long dark winter nights give way to the long summer evenings, and so at two points in the calendar year both the hours of daylight and darkness are of equal length. These two moments are six months apart and are known as the Equinox. The term equinox is Latin stemming from equal and night.

This year’s equinox falls around the 21st March and marks the commencement of spring. Six months later the 22nd of September the second equinox occurs and marks the first day of autumn.

Something rather special happens on these two moment of the year that you can try for yourself using a shadow stick. Through most of the year the line drawn through the markers used to indicate the end on the shadow cast by sun’s rays or the moons reflection of the sun, from its surface upon the stick, form a curve. During the summer the curve seemingly looks like a happy smile below the shadow stick and in the winter, it looks sad, which makes it easy to remember.

The straight equinox shadow line

During the equinox, however it is a straight line that runs from west to east. Standing with your feet up to the line with the shadow stick in front of you, you will be facing south. This is true regardless of where you stand along the line. On the curved lines however this could have you facing South West or South East.

First two markers of the morning with the compass clearly showing south 

Compass half way along the line at the midday marker, showing south and intersecting with the Shadow stick.

Compass towards the end of the afternoon, again showing south.

This is a direct effect of the earth revolving one revolution on an axis of 23.5 degrees in a 24 hour period as it revolves around the sun in 365 days.

You can read about shadow sticks using the moon as well as the sun in one of our earlier blogs here.

Jay Jenner