I'm looking to plot day/night on a Google map, for an arbitrary point in time. I'm familiar with generating map tiles; I'm just looking for an algorithm to tell me whether a particular point on the globe is currently in daylight or darkness, or to otherwise plot the curve of the day/night interface onto the map.
I've done some searching, but it's possible I don't even know enough about the problem domain here to know what terms to search for!
Any ideas? Doesn't have to be perfect — basically, I'm comparing Flickr geolocation data of sunrise and sunset photos (and their "date taken" timestamps) with reality, and this is to help me visualise it.
Best Answer
This page gives equations good to 1 degree. It looks like this code calculates it too but I didn't actually check.