I saw a shadow of a catenary (or close enough) on a cylinder and wondered about the shape. Specifically, it was a powerline strung between 2 utility poles, and the sun angle would have been around 45 degrees or so, and the cylindrical grain bin was between and north (I am in northern hemisphere) of the poles. The powerline I assume is a catenary, although it would be close to a parabola, right?, and the grain bin would be a vertically oriented cylinder to pretty high precision (neglecting corrugations). The shadow of the powerline appeared to define a plane on the grain bin, but that is just to me and my bifocals. And the shadow also looked from a distance to be a segment of a circle, but I find that difficult to fathom, as how would a circular cylinder (so to speak) cancel out (so to speak) the catenariness of the shadow? Anyhow, is this an interesting (and previously identified) shape?