Snowflakes’ shape and size are influenced by the conditions in which they’re formed – temperature, air currents, humidity, etc. But except in rare occurrences, they will always be six-sided. Somehow, though, artists and illustrators keep screwing this up on everything from Christmas cards to ugly sweaters to store displays, giving the flakes anywhere from five to eight sides. Thomas Koop, a professor of chemistry at the University of Bielefled in Germany who specializes in ice crystal formation, was able to ignore the “corruption” of real, natural snowflakes by “incorrect 'designer' versions” for a while, but there’s only so much a man can take. When he spotted an eight-sided flake in the science journal Nature last year, Koop fired off a letter to the editor, which the journal printed last Christmas Eve.
In his letter, Koop explained that the hexagonal shape of snowflakes has been known for 400+ years, ever since German astronomer/mathematician Johannes Kepler published his treatise “On the Six-Cornered Snowflake.” So why are snowflakes shaped like that? Koop told LiveScience last year that “the hexagonal crystal lattice is the lowest energy form of water at cold ambient conditions. As the molecular building blocks arrange themselves into a hexagonal structure on the molecular scale, so do snow crystals exhibit this hexagonal symmetry also on the macroscopic scale.”