Here is a reference to a program that crashed based on the phase of the moon for slightly different reasons: http://www.catb.org/jargon/html/P/phase-of-the-moon.html

The one that I described I first remember hearing about in undergrad. I heard it from an astronomy student. I guess that makes it an urban legend, but a highly believable one. In my experience inexperienced programmers are very good at unexpectedly repurposing whatever they happen to know for new purposes. And in an astronomy department it is easy to find inexperienced programmers with astronomical routines at hand.