From late 1977 people on this island in the mouth of the Amazon began complaining of glowing objects that hung over houses at night and put a narrow beam down on them. They came to the clinic with burns, dizziness and anaemia; the local doctor, Wellaide Cecim Carvalho, kept the records. The Brazilian Air Force sent a team — Operação Prato, Operation Saucer, which worked for several months. The military collected hundreds of pages of reports, photographs and cine film. The material was declassified in the 2000s and passed to the Brazilian National Archives. It names no cause; some doctors put the symptoms down to panic and poor diet, and some did not. Many families left the island at the time.

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The Min Min Lights

A town deep in Queensland that gave its name to the lights seen on the roads of the burnt west: glowing spheres that follow a car or a rider and keep their distance for hours. Aboriginal people described them before Europeans arrived. In 2003 the physicist Jack Pettigrew showed experimentally that under a temperature inversion a light source beyond the horizon can appear as a nearby object — an elegant explanation that does not cover every case.