While scientifically correct, he's also a little pedantic.
I wonder how many manifestos are the result of someone snapping?
I wrote a fun little web app to draw snowflakes a few weeks ago: http://www.create-a-snowflake.com/ . I settled on 8 sides, although the first version had an option to have anywhere from 4 to 20 sides.
I agree with the heart analogy.
Given that different conditions produce different crystals (see for instance the description for the "capped columns"), my best guess is simply that each of the 6 sides experienced all-but-identical growth conditions, and thus the correct question is rather why would they be different?
Someone else mentioned 12- and 3-siders, and trying to Google up those images is how I got to that site in the first place. See: http://www.its.caltech.edu/~atomic/snowcrystals/unusual/unus... (Note you have to "-paper" in the Google search, or you'll just be hammered with instructions for paper snowflakes of varying degrees of scientific inauthenticity.)
Edit: Ah, the site addresses that: http://www.its.caltech.edu/~atomic/snowcrystals/faqs/faqs.ht...
"While [a snowflake] grows, the crystal is blown to and fro inside the clouds, so the temperature it sees changes randomly with time. But the crystal growth depends strongly on temperature (as is seen in the morphology diagram). Thus the six arms of the snow crystal each change their growth with time. And because all six arms see the same conditions at the same times, they all grow about the same way. The end result is a complex, branched structure that is also six-fold symmetric. And note also that since snow crystals all follow slightly different paths through the clouds, individual crystals all tend to look different."
And see also the next question, "What synchronizes the growth of the six arms?". I'm hitting the limit of what I feel comfortable just copying and pasting into HN.
My alternate guess is that snowflakes actually aren't symmetrical, although they display many local 6-way symmetries.
Edit: ah, the answer by jerf verifies that these guesses were reasonable.
If the code was written in a sane way you would be able to skim through it in two minutes and have a good overview of how a snowflake is made. Given that it would probably take a good hour at least to understand it and I am only so-so interested in learning I wont bother. This is especially sad given that this is coming out of edu where I would presume that part of the purpose is to teach how a snowflake is grown.
I wrote an iPhone app last year that allowed you to create virtual paper snowflakes, and I didn't realize until later that all the flakes it created were "abominations" that had 8, 10, or 12 sides.
I was a little surprised by the amount of feedback I received explaining to me exactly what was wrong with the snowflakes in my app. Unfortunately, I haven't gotten around to fixing this egregious error just yet ;) .
I won't say it's impossible to naturally form it, but I am certain it wouldn't involve clouds of water vapor. Perhaps around proteins or some biological process...
It's entirely likely this symbol came from pictures of stars, as opposed to real ones.
Surely that makes you cringe at least a little bit :)