After losing my way last summer in a tiny town best known as the deathplace of Billy the Kid, I eventually located the right desert highway. Outperforming the alleged aliens who, seventy years before, had allegedly crashed their alleged spacecraft nearby, I swept past a welcome sign decorated with—in honor of a cow town’s real and imagined pasts—cattle and a flying saucer, and reached Roswell, New Mexico, in one piece:

The City of Roswell invites ufo enthusiasts and skeptics alike to join in the celebration of one of the most debated incidents in history.

History is not what it was.

Alien...