Stellating in 2 DimensionsI think you will find the stellation of polyhedrons much easier to understand after seeing the process of stellation applied to polygons. So, to that end, we start with the regular Pentagon and extend the edges until they meet.The result is the familiar 5pointed star (Pentagram). You can extend the edges further, but they never meet again, so apparently there is only one stellation of the Pentagon. 
As a second example, let's try stellating the Octagon. Extending the edges
until they first intersect produces an eightpointed star shape. This is the
first stellation of the Octagon.
Note, however, this shape can also be interpreted as a Compound of two equal squares, one rotated 45 degrees from the other. Some of the stellations of polyhedra that we will look at also have dual interpretations. If you extend the edges of this new shape, you get another eightpointed star shape. This is the second stellation of the Octagon. The appropriateness of the term Stellation is becoming clear! Here are a couple of exercises for you: First, convince yourself that the Triangle and Square have no stellations, that the Pentagon and Hexagon have one stellation, and that the Heptagon and Octagon have two stellations. Second, see if you can come up with a formula for how many stellations a regular Ngon has. 

Consider now the other Platonic Solids. You will find that the Tetrahedron and Cube have no stellated forms; if you extend their faces they never reintersect.
The remaining two have several stellated forms each. The Dodecahedron has three, and it turns out that they are quite special (see The KeplerPoinsot Polyhedra), and the Icosahedron has an incredible 59 stellated forms!
We can also stellate the Archimedian solids, but little is known about most of these. It is here that we unexpectedly meet the boundary of contempory mathematics!
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