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Icosahedron Stellations


Applying the stellation process to a regular icosahedron gives

 20+30+60+20+60+120+12+30+60+60

cells of 10 different shapes and sizes (Wenninger 1989, p. 41).

IcosahedronStellations

After application of five restrictions known as Miller's rules to define which forms should be considered significant and distinct (Coxeter et al. 1999, pp. 15-16), 59 stellations (including the original regular icosahedron itself) are possible (Coxeter et al. 1999). These stellations are illustrated above are given in the original ordering of Maeder (1994).

18 of the 59 stellations are fully supported. Of these, 16 are reflexible and 2 are chiral (Webb).

Of the 59 icosahedron stellations, 32 have full icosahedral symmetry and 27 are enantiomeric forms (Coxeter et al. 1999, pp. 64-65). One is a Platonic solid (the icosahedron itself), one is a Kepler-Poinsot polyhedron, four are polyhedron compounds, and one is the dual polyhedron of an Archimedean solid. Note that the first real stellation (stellation #2 in Coxeter's counting) is that obtained by cumulating the icosahedron until the faces of each triangular pyramid lie parallel to the surrounding original faces. This gives fairly small spikes, and results in a solid known as the small triambic icosahedron. Note also that the great stellated dodecahedron is not an icosahedron stellation since the faces of its groups of five triangular pyramids do not lie in the same plane (even though they appear very close to it).

IcosahedronFacePlanes

The original icosahedron, its 20 facial planes, and the intersections of those planes with the facial plane of the "top" face are illustrated above.

IcosahedronStellationDiagram

The stellation diagram showing the 18 lines of intersections of one face with the 18 other nonparallel faces is shown above, together with the regions into which these intersections divide the plane (Coxeter et al. 1999, p. 17).

IcosahedronStellationDiagramSimplified

The numbering of the regions can be simplified by writing 2 for both 2 and 2, 4 for 4 and 4, 11 for 11 and 11, and 13 for all of 13, 13, and 14 (Coxeter et al. 1999, pp. 18-19).

The following table (extending Coxeter et al. 1999, pp. 13 and 64-65) summarizes different orderings and notations used by a number of authors. The newer Maeder numbering ("Stellated Icosahedra" web page, "Fifty-Nine Icosahedra" Demonstration) orders by increasing circumradius R. Rogers ("Playing with Stellations of the Icosahedron" Demonstration) uses the ordering and §3 notation of Coxeter et al. (1999). Stellations with Coxeter index 1-32 are amphichiral, while those with index 33-59 are chiral stellations listed in dextro form. To obtain the laevo form, change Roman to italic and vice versa in both "§2" and "§3" notations (Coxeter et al. 1999, pp. 64-65).

MathWorld nameCoxeterCoxeter §2Coxeter §3Coxeter plateCoxeter nameWenningerWenninger nameWheelerBrücknerMaederMaeder R
regular icosahedron10AIicosahedron4111
small triambic icosahedron21BItriakisicosahedron26triakis icosahedron2Fig. 2, Taf. VIII22
octahedron 5-compound32CIfive octahedra233Fig. 6, Taf. IX33
43 4DI4Fig. 17, Taf. IX54
55 6 7EII169
68 9 10FII272nd stellation192135
great icosahedron711 12GIIgreat icosahedron41great icosahedron11Fig. 24, Taf. XI1154
echidnahedron813HIIIcomplete stellation42final stellation12Fig. 14, Taf. XI459
93^' 5e_1IV3712th stellation67
105^' 6^' 9 10f_1IV3014
1110^' 12g_1IV294th stellation211024
123^' 6^' 9 10e_1f_1V2410
133^' 6^' 9 12e_1f_1g_1V202620
145^' 6^' 9 12f_1g_1V3223
154^' 6 7e_2VI146
167^' 8f_2VI22833
178^' 9^' 11g_2VI2255
184^' 6 8e_2f_2VII1532
194^' 6 9^' 11e_2f_2g_2VII2844
207^' 9^' 11f_2g_2VII305th stellation1945
214 5De_1VIII327th stellation1078
tetrahedron 10-compound227 9 10Ef_1VIII25compound of ten tetrahedra8Fig. 3, Taf. IX1812
238 9 12Fg_1VIII316th stellation17Fig. 3, Taf. X2339
244 6^' 9 10De_1f_1IX2711
254 6^' 9 12De_1f_1g_1IX2921
inwardly augmented dodecahedron267 9 12Ef_1g_1IX9Fig. 26, Taf. VIII2022
273 6 7De_2X283rd stellation5125
285 6 8Ef_2X18Fig. 20, Taf. IX1734
2910 11Fg_2X338th stellation14947
303 6 8De_2f_2XI349th stellation131331
313 6 9^' 11De_2f_2g_2XI2543
325 6 9^' 11Ef_2g_2XI3146
335^' 6^' 9 10f_1XII3510th stellation3313
343^' 56^' 9 10e_1f_1XII3611th stellation3415
354 5 6^' 9 10De_1f_1XII3516
365^' 6^' 910^' 12f_1g_1XIII3925
373^' 5 6^' 9 10^' 12e_1f_1g_1XIII3914th stellation4526
384 5 6^' 9^' 10^' 12De_1f_1g_1XIII4727
395^' 6^' 8^' 9^' 10 11f_1g_2XIV5056
403^' 5 6^' 8^' 9^' 10^' 11e_1f_1g_2XIV5457
414 5 6^' 8^' 9^' 10 11De_1f_1g_2XIV5858
425^' 6^' 7^' 9^' 10 11f_1f_2g_2XV4851
433^' 5 6^' 7^' 9^' 10 11e_1f_1f_2g_2XV5252
444 5 6^' 7^' 9^' 10 11De_1f_1f_2g_2XV5653
454^' 5^' 6 7 9 10e_2f_1XVI4015th stellation4219
463 5^' 6 7 9 10De_2f_1XVI4018
tetrahedron 5-compound (dextro)475 6 7 9 10Ef_1XVIfive tetrahedra24compound of five tetrahedra73617
tetrahedron 5-compound (laevo)5 6 7 9 10Ef_16Fig. 11, Taf. IX
484^' 5^' 6 7 910^' 12e_2f_1g_1XVII5730
493 5^' 6 7 9 10^' 12De_2f_1g_1XVII5329
505 6 7 9 10^' 12Ef_1g_1XVII4928
514^' 5^' 6 8 9 10e_2f_1f_2XVIII3813th stellation4338
523 5^' 6 8 9 10De_2f_1f_2XVIII4137
(dextro)535 6 8 9 10Ef_1f_2XVIII153736
(laevo)5 6 8 9 10Ef_1f_216
544^' 5^' 6 8 9 10^' 12e_2f_1f_2g_1XIX5942
553 5^' 6 8 9 10^' 12De_2f_1f_2g_1XIX5541
565 6 8 9 10^' 12Ef_1f_2g_1XIX5140
574^' 5^' 6 9^' 10 11e_2f_1f_2g_2XX4650
583 5^' 6 9^' 10 11De_2f_1f_2g_2XX4449
595 6 9^' 10 11Ef_1f_2g_2XX3848

Coxeter stellation number 30 (De_2f_2) corresponds to the hull of the medial triambic icosahedron and great triambic icosahedron (Wenninger 1983, pp. 45-50).


See also

Archimedean Solid Stellations, Dodecahedron Stellations, Icosahedron, Stellation

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References

Allanson, B. "The Fifty-Nine Icosahedra." http://members.ozemail.com.au/~llan/i59.html.Ball, W. W. R. and Coxeter, H. S. M. Mathematical Recreations and Essays, 13th ed. New York: Dover, pp. 146-147, 1987.Brückner, M. Vielecke und Vielflache, Theorie und Geschichte. Leipzig, Germany: Tuebner, p. 206, 1900.Bulatov, V. "Stellations of Icosahedron." http://bulatov.org/polyhedra/icosahedron/.Coxeter, H. S. M.; Du Val, P.; Flather, H. T.; and Petrie, J. F. The Fifty-Nine Icosahedra. Stradbroke, England: Tarquin Publications, 1999.Hart, G. "59 Stellations of the Icosahedron." http://www.georgehart.com/virtual-polyhedra/stellations-icosahedron-index.html.Inchbald, G. "In Search of the Lost Icosahedra." Math. Gaz. 86, 208-215, 2002. Maeder, R. E. "Fifty-Nine Icosahedra." https://demonstrations.wolfram.com/FiftyNineIcosahedra/. Maeder, R. E. "Icosahedra." http://library.wolfram.com/infocenter/MathSource/4494/. Also http://www.inf.ethz.ch/department/TI/rm/programs.html. Maeder, R. E. "Index to Old Numbering Scheme." http://www.mathconsult.ch/static/icosahedra/index-old.html. Maeder, R. E. "The Stellated Icosahedra." Mathematica in Education 3, 5-11, 1994. http://library.wolfram.com/infocenter/Articles/2519/. Maeder, R. E. "Stellated Icosahedra." http://www.mathconsult.ch/showroom/icosahedra/. Rogers, M. "Playing with Stellations of the Icosahedron." http://demonstrations.wolfram.com/PlayingWithStellationsOfTheIcosahedron/.Update a linkWang, P. "Polyhedra." http://www.ugcs.caltech.edu/~peterw/portfolio/polyhedra/Webb, R. "Enumeration of Stellations." http://www.software3d.com/Enumerate.php.Webb, R. "Icosahedron." http://www.software3d.com/Icosahedron.php.Wells, D. The Penguin Dictionary of Curious and Interesting Geometry. Middlesex, England: Penguin Books, pp. 77-78, 1991.Wenninger, M. J. Dual Models. Cambridge, England: Cambridge University Press, 1983.Wenninger, M. J. Polyhedron Models. New York: Cambridge University Press, pp. 41-65, 1989.Wheeler, A. H. "Certain Forms of the Icosahedron and a Method for Deriving and Designating Higher Polyhedra." Proc. Internat. Math. Congress 1, 701-708, 1924.

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Icosahedron Stellations

Cite this as:

Weisstein, Eric W. "Icosahedron Stellations." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/IcosahedronStellations.html

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