Well this may be ignorant of me, but I am 20 years old and I have only just today discovered that some of the world (namely the US but probably more) marks the change in the seasons by the solstices and equinoxes. I cannot believe I didn't know that. I just assumed that everyone did the same as we do in Australia, which is to say that yesterday marked the 1st day of Summer for us (1st Dec 2008).

The extent of my use of the solstice on the 21st, has been, until today, that it is the longest day of the year.

I constantly forget and am subsequently surprised that there are so many differences in the small everyday things we do over the world ^_^