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xkcd #2897: Light Leap Years
(imgs.xkcd.com)
Alt text:
When Pope Gregory XIII briefly shortened the light-year in 1582, it led to navigational chaos and the loss of several Papal starships.
They skip leap years every now and then. And then skip the skip. Etc. The rotation of the earth around the sun and the spin of the earth on its axis simply don't line up into a nice number.
Oh okay. Yeah I only have that rule of "every 4 years" in my head. I did some other programming exercise way back where we had some other rule, but I was thinking that it would end up being the same.