Snowflakes

Yesterday I was confronted with my kid asking whether all snowflakes have 6 sides. Turns out the answer is yes, or more precisely "A snowflake always has six lines of symmetry, which arises from the hexagonal crystal structure of ordinary ice" (quote from the linked page).

What is however more amazing are the photos of snowflakes on the NOAA website, an archive of the work of Wilson Bentley, whose hobby was photographing snowflakes, and who developed the method and apparatus for photographing them before they melted, and made more than 5000 pictures of them at the end of 19th and beginning of the 20th century.

Amazing.