It's sung, of course, by Fred Rogers, or as we all call him, "Mister." He is our diva (divo?), and his theme is Wonder, like ours.
This remix comes from Washington-based musician John Boswell's Symphony of Science Series, which fairness requires me to say. But I like to think Mr. Rogers was singing this song only, and particularly to me, because (as he told me, over and over) "I am very, very, very special."