The rest of the story is speculation, successive stages of Wilson’s inferences.
The matter-of-fact description of the marvelous of H. Wells, the poetic evocation of unknown places of Lord Dunsany, and the immense vistas of space and time of the philosopher Olaf Stapledon lie cheek-by-jowl with artificial suspense devices, awkward sentimentality, schoolboy silliness, and melodramatic manipulation of such hoary motifs as the “stranded astronaut” or the “end of the world” in his less distinguished fiction.
At its best, however, Clarke’s work shows glimpses of man’s rise to interplanetary civilization or evokes the wonder, in suitably subdued tones, of his confrontation with extraterrestrial intelligences.
His father showed him the earth from moon’s surface and told him that earth was destroyed in a nuclear war.
The people living on moon have the goal to restore earth now as they are the last of human race.