User blog comment:Paleomario66/Compilation of Mario's Feats/@comment-33067344-20180715110646

>"The Power Stars also allow Bowser to create multiple galaxy-sized realms inside paintings. the Throwback Galaxy is, in fact, the Whomp's Fortress from this game, which supports that these realms are galaxy-sized."

I don't see how a cameo appearence proves that the realms are galaxy-sized, taking into account that there's black holes in the Throwback Galaxy.