Farewell message

A visiting alien scholar occupies an airport runway while studying human customs, paying for favors with superior condescension and advanced gadgets. At a public farewell address he warns that civilizations that do not abandon warfare destroy themselves, citing stellar novas as evidence. During the speech observers notice an extremely bright star that turns out to be a nova whose light took years to arrive; the alien recognizes it as the explosion of a world he personally knew and is shaken into silence and humility. Confronted with proof that war can annihilate a culture, he decides to postpone his departure and remain among humans, visibly altered by grief and uncertainty.