What is a Fibonacci Spiral?
It’s a special form of the “golden spiral”, which is a special form of a logarithmic spiral. A logarithmic spiral has a radius that increases at a rate proportional to the current radius, so it gets larger at an ever-inceasing rate. The radius of a golden spiral inreases by the factor 1.618… every quarter revolution, a number called the golden ratio which derives from the Fibonacci series. Successive pairs of terms of the Fibonacci series (1,1,2,3,5,8,13, etc.) have ratios that converge on the golden ratio (see the ref.) The Fibonacci spiral’s radius increases exactly as successive terms of the Fibonacci series do.
