I'd like to set up functions to calculate sunrise and sunset times. I don't need huge precision; just a rough estimate (like within a half hour) would do. But then again, I certainly wouldn't complain about a solution with high precision.

Ideally you'd just send the function latitude and longitude coordinates. Something like:
Code:
Public Function Sunrise(pdblLatitude As Double, pdblLongitude As Double) As Date
End Function

Public Function Sunset(pdblLatitude As Double, pdblLongitude As Double) As Date
End Function
Google turned up a ton of possible ways to go, none of which made a lick of sense to me.