I spent last weekend visiting friends in Marion, Massachusetts, a picturesque little town cut out of the mossy pine forests on the shores of Buzzards Bay, from which Cape Cod stretches out. It rained a lot, but Sunday evening was clear and breezy enough to blow the mosquitoes away, so we walked out to the water to watch the sun set. After a couple minutes of looking west, though, we turned our heads to the north and gasped and said "Whoa!" just like a certain resident of Yosemite, California I'm sure you're well familiar with by now. Because there was a rainbow in the sky. And [...]