Asterism

Noun

1. An unofficial constellation (small group of stars that forms a visible pattern).

   "The Big Dipper, Summer Triangle, and Orion's Belt are asterisms."

2. A rarely used typographical symbol of three asterisks arranged in a triangle, ⁂, used to call attention to a passage or to separate subchapters in a book. Distinct from a dinkus which also uses asterisks to separate.
3. A star-shaped figure exhibited by some crystals by reflected light (as in a star sapphire) or by transmitted light (as in some mica).