An ellipse (blue) with a collection of its centers of curvature (red) that outlines the evolute of the ellipse. The four extreme values of the radius of curvature correspond to four cusps in the evolute.
<a href="//commons.wikimedia.org/wiki/User:Lieven_Smits" title="User:Lieven Smits">Lieven Smits</a>
CC BY-SA 3.0
own work, constructed using Microsoft Excel