Origami Day

What the day is

Origami Day is observed on November 11. The date is often explained by the shape of the digits, four ones resembling folded paper cranes, and it coincides with a Japanese paper-themed observance.

Origin and background

Paper folding developed in Japan over centuries, initially for ceremonial and religious purposes where folded paper marked offerings and formal gifts. Paper was expensive, and folding it was a mark of occasion rather than a pastime.

The thousand-crane tradition, in which folding a thousand paper cranes is said to grant a wish, acquired a specific modern meaning through Sadako Sasaki, a girl who developed leukemia after the bombing of Hiroshima and folded cranes during her illness. Paper cranes are now left in enormous numbers at peace memorials.

What has changed most recently is origami's standing as mathematics and engineering. Folding is governed by rules that can be stated formally, and the field produced results that surprised mathematicians: origami construction can solve problems impossible with compass and straightedge, including trisecting an angle and doubling the cube.

The engineering applications follow from a practical property. A folded structure can be compact for transport and deploy into a much larger rigid form, which is precisely the problem faced by spacecraft. Folding patterns derived from origami research have been used for solar arrays and telescope components, and in medicine for stents that travel narrow and expand in place. Airbag folding uses related work.

How to take part

• Fold a crane. Instructions are everywhere and it takes about fifteen minutes the first time.
• Use proper paper: thin and crisp, cut exactly square. Most first failures are paper failures.
• Crease sharply, with a fingernail or a bone folder. Soft creases compound into a mess.
• Try a modular design, where identical units lock together without glue.
• Look up the Miura fold, which is the one that went to space, and try folding it from a sheet of paper.