Pythagorean Mysteries....

Penrose Tilings, the Golden Rectangle, and the Pentagram share geometric properties having to do with the ratio "phi":

j = (1+ 51/2)/2 = 1.618....

Examples of Penrose tilings are shown in the background images. While the golden rectangle has the following shape (which is inscribed internally to indicate its iterative geometric properties):

Golden RectangleGolden Rectangle

A pentagram you've seen (the red star between white and yellow pentagons):