Stella, a computer program

Computer program

A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...

 available in three versions (Great Stella, Small Stella and Stella4D) was created by Robert Webb of Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. The programs contain a large library of polyhedra which can be manipulated and altered in various ways.

Polyhedra in Great Stella's library include the Platonic Solids, the Archimedean solid

Archimedean solid

In geometry an Archimedean solid is a highly symmetric, semi-regular convex polyhedron composed of two or more types of regular polygons meeting in identical vertices...

s, the Kepler-Poinsot solid

Kepler-Poinsot solid

In geometry, a Kepler–Poinsot polyhedron is any of four regular star polyhedra. They may be obtained by stellating the regular convex dodecahedron and icosahedron, and differ from these in having regular pentagrammic faces or vertex figures....

s, the Johnson solid

Johnson solid

In geometry, a Johnson solid is a strictly convex polyhedron, each face of which is a regular polygon, but which is not uniform, i.e., not a Platonic solid, Archimedean solid, prism or antiprism. There is no requirement that each face must be the same polygon, or that the same polygons join around...

s, some Johnson Solid near-misses

Near-miss Johnson solid

In geometry, a near-miss Johnson solid is a strictly convex polyhedron, where every face is a regular or nearly regular polygon, and excluding the 5 Platonic solids, the 13 Archimedean solids, the infinite set of prisms, the infinite set of antiprisms, and the 92 Johnson solids.The set of...

, numerous compounds including the uniform polyhedra

Uniform polyhedron

A uniform polyhedron is a polyhedron which has regular polygons as faces and is vertex-transitive...

, and other polyhedra too numerous to list here. Operations which can be performed on these polyhedra include stellation

Stellation

Stellation is a process of constructing new polygons , new polyhedra in three dimensions, or, in general, new polytopes in n dimensions. The process consists of extending elements such as edges or face planes, usually in a symmetrical way, until they meet each other again...

, faceting, augmentation, dualization (also called "reciprocation"), creating convex hull

Convex hull

In mathematics, the convex hull or convex envelope for a set of points X in a real vector space V is the minimal convex set containing X....

s, and others.

All versions of the program enable users to print net

Net (polyhedron)

In geometry the net of a polyhedron is an arrangement of edge-joined polygons in the plane which can be folded to become the faces of the polyhedron...

s for polyhedra. These nets may then be assembled into actual three-dimensional polyhedral model

Polyhedron model

A polyhedron model is a physical construction of a polyhedron, constructed from cardboard, plastic board, wood board or other panel material, or, less commonly, solid material....

s of great beauty and complexity.

In 2007, a Stella4D version was added, allowing the generation and display of four-dimensional polytopes (polychora), including a library of all convex uniform polychora

Uniform polychoron

In geometry, a uniform polychoron is a polychoron or 4-polytope which is vertex-transitive and whose cells are uniform polyhedra....

, and all currently known nonconvex star polychora, as well as the uniform duals. They can be selected from a library or generated from user created polyhedral vertex figure

Vertex figure

In geometry a vertex figure is, broadly speaking, the figure exposed when a corner of a polyhedron or polytope is sliced off.-Definitions - theme and variations:...

files.

Release history

• v1.0 - 20 August 2001 - First release of Stella
• v2.0 - 12 September 2002
• v3.0 - 12 June 2005
  • v3.5 - 16 March 2006
    • v3.5.1 - 10 May 2006
• v4.0 - 13 March 2007 - newest version (Including new "Stella4D")
  • v4.1 - 24 March 2007
  • v4.2 - 27 June 2007
  • v4.3 - 2 November 2007
  • v4.4 - 11 January 2008

External links

• Stella homepage
• Stella: Polyhedron Navigator - Paper published in Symmetry: Culture and Science, Volume 11, Numbers 1-4, 231-268, 2000 contents (Note: journal was back-dated. Paper actually written 2003)
• Stella Models - Paper published in Symmetry: Culture and Science, Volume 13, Numbers 3-4, 391-399, 2002 contents (Note: journal was back-dated. Paper actually written 2004)