The shape of a football?

ball hits the net

Ask most people, they will say a football is “round”, but this is not the whole story. An official soccer ball, to be approved by the Fédération Internationale de Football Association (FIFA), must be a sphere with a circumference between 68 and 70 centimeters, with at most a 1.5 percent “deviation from sphericity” when inflated to a pressure of 0.8 atmospheres. Of course, you knew that.

In 1836, Charles Goodyear patented the manufacturing process of vulcanized rubber, a milestone in the evolution of the soccer ball. But it wasn’t until 1855 that he created the rubber match ball. Before then, most balls were an inflated pig’s bladder encased in leather. Those balls were not regular and so were hard to control. The design of the soccer ball was further developed by H.J Lindon in 1862 when he produced a ball that used an inflatable “rubber bladder” to hold its shape.

During the 1960s, footballs were redesigned to the form we see today, a shape known as a “truncated icosahedron”. An icosahedron is a polyhedron with 20 faces and “truncated” means each point is cut off to create a pentagon. This is an Archimedean solid but the only one of these shapes that does not contain triangles or squares. It has 12 regular pentagonal faces (black), 20 regular hexagonal faces (white), 60 vertices (corners) and 90 edges. You can find out more about this beautiful shape here.

Soccer ball manufacturers realised that a ball composed of leather hexagons and pentagons created a perfectly spherical shape that held its form. The design was coined the “buckyball,” and it is still the most common ball on soccer fields today.

The buckyball made its international debut at the 1970 World Cup Finals in Mexico. The historical ball was called the “Telstar” (name after an early satellite) and it was manufactured by Adidas. It was designed with a black and white pattern so it would be visible on the black and white televisions of the era. Although we have color TV now, the iconic black and white pattern still remains popular today.

The truncated icosahedron has uses beyond the game of football. They can be used to create a strong architectural structure known as “geodesic domes”. The shape also corresponds to the geometry of the Carbon fullerene C60 (“buckyball”) molecule, where atoms link up in five and six pointed rings – both shapes that carbon readily forms into.

So next time you see the net bulging, you can appreciate the geometry behind the ball….

As a tenuous connection to Sheffield, have a look at the massive light hanging in the City Hall – it is the same shape as a football!

 

Do you have more information about this that we could add? Are any of the facts wrong? Please get in touch if so.

Source: Nick Robinson
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