Thanks for your replies, all, and as a matter of fact, Luckydog, I happened to also take a zoomed-in version of the sunset behind that tree (lacking in quality somewhat because of the zoom). Here it is:
And jasonmac, I do agree: this not only looks just half, it is only half. I was mad at the relatively "normal" angle of the so-called "wide-angle position" of the little lense that my new little Canon Powershot has got and sorely longed for my "regular" Canon (film) with its real and true wide angle lense, but alas! it was not with me for lack of film. Later I thought: had I only read the manual to the digital camera carefully enough, I might have tried my first "stitching a pano", but...
Too true! The vapour trail made such a perfect arch all across that part of countryside that night. Well, must study my handbook a bit closer! Lesson learned.