Josep Rey Nadal

MMACA (Museu de Matemàtiques de Catalunya)
La Garriga, Catalonia, Spain

Mathematician, former teacher, artist, mathematical and creative museographer of Mathematics Museum of Catalonia.

Sphere of segments and colors
Sphere of segments and colors
55 x 55 x 55 cm
Cypress wood and steel screws

This object, with 12 pentagons and 20 triangles, can be considered a rotegrity.
It's interactive and it's build with 30 similar pieces. No tools are needed, only your hands.
These pieces are decorated with 5 colours, 6 of each one, and can be arranged however the user likes.
One of the possible arrangements is with all the pentagons painted differently.
From the 24 cyclical permutations of 5 colours, you can get 12, all of them with the same parity.
There are 20 possibilities to arrange 3 colours of 5 to ensemble the triangles and all of them are possible. Thus, all the triangles can be different.
This object has chirality. You can build the object or its specular image.