An engaging group for the Beginner’s Guide to Natural Navigation course at the Royal Geographical Society yesterday. Diverse in age and interests as always. When we were discussing the difference in the sun’s behaviour between the solstices and equinox it felt more poignant that we are so close to the autumnal equinox itself. We looked at a model of the Earth orbiting the sun, then shifted our attention to shadows. A couple of days ago I took advantage of the sunshine to practice what I preach.
This chalk line in this picture shows the shadow tips joined over a period of a few hours on the morning of the 21st September. The line comes very close to a straight line, but even on the equinox it is never a perfectly straight line – unless you happen to be standing on the equator when the sun would rise due east, pass directly overhead and then set due west.
Tags: equinox, navigation course, royal geographical society, shadow stick, solstices
