I'm adding a plot hook about some murders that take place on each winter and summer solstice. (It's up to the characters to find out that a mysterious wizard who lives south of town comes into town every six months... hmmm...)
The characters may or may not realize that the summer solstice is only three days away. I'm having trouble deciding which skill they would use for it.
My first reaction was perception. Then I thought no, they aren't actually SEEING anything (unless they happen to walk by a calendar, but I don't imagine there's many of those.)
Then I thought insight, maybe history. But they don't really apply either.
Now, I'm leaning toward nature, as someone in tune with nature would surely be conscientious of when the solstices were.
The players in the party are a paladin, sorcerer, and wizard, so not particularly "naturey" folks here.
What DnD 4e skill would this challenge be most appropriate under?