OK, I read this one about 1967 I guess, it was juvenile fiction I suppose. There is this kid, who lives on a nicer planet that ours. In the evening the people go out to watch the sun set, & see the stars & etc.. Then something happens to the boy, and he is trans substantiated off to USA circa 1960s. More of a rural setting, not "the sixties" of popular culture. He is taken in by a kind family, but not before somehow running afoul of some assholes. Anyway, the good guy/bad guy situation progresses to some climax I know longer recall, and ultimately the boy and his adopted family get re trans substantiated back to the groovy planet with the sunsets. Any ideas?