When my wife and I bought our house two and half years ago, one of the features that appealed to us was a tree that stood grandly in the yard, its branches reaching well over the house. The problem, we soon realized, is it stood too grandly and too close, pressuring the foundation and encouraging moss on the roof. We cut it down a little over a year ago and since then I’ve noticed that regardless of the season, the bulk of the sun’s transit across the sky each day baths light upon the roof once shaded by the...