On a white restaurant tablecloth in San Francisco, under the glow of a stained-glass dome ceiling with images of laurels, fleurde-lis, and a ship, rested a portion of metal the size of a shallot. Around it one day in the summer of 2018, three men were having lunch. Jacques Vallée, a French information scientist, was explaining to Max Platzer, editor of a top aeronautics journal, how the metal had come into his possession. The story wound back more than four decades, he said serenely, to an unexplained episode in Council Bluffs, Iowa.
On a cold Saturday night in late 1977, fire-fighters and police had responded to calls about a roundish, reddish object with blinking lights that hovered above the treetops in a public park, then dumped a bright mass onto…
