Many of you will have stood upon the 0° longitude line, our very own Meridian in Greenwich. Quite a few will have crossed the 0° latitude line, the equator. Some will have heard of the 47th parallel, famous for defining part of the border between the USA and Canada.
Many have drawn a right angle and some view everything under a different angle.
But do you know the magic of the 137.5° angle?
A 137.5° angle is known as the golden angle, because it occurs when cutting a circle into two pieces under the golden ratio: 360° – 360° / φ ≈ 137.5°, where the golden ration φ ≈ 1.61803, or (1 + sqrt(5))/2 precisely.
Many plants grow according to the golden angle, for example by growing a new leaf rotated around the stem from the previous leaf by 137.5°. The effect is that the leaves grow with minimum overlap, therefore maximising sun exposure on every leaf. Not just little overlap but the minimum overlap mathematically possible. Isn’t that clever?
I don’t think our fruit trees show much appreciation for the golden angle, but one might still find other more mathematically-minded plants out there. I am inclined to give the nettles a closer look, or the Giant Hogweed and its relatives, also the horsetail’s thin leaves, raspberries and blackberries, or the dandelion and hop flower maybe?