A warm September evening on the lake. Kariba sits on the Zimbabwean shore of the biggest man-made body of water in Africa, and after dark the only things in the sky are stars, the occasional charter flight, and the glow of the fishing rigs out on the water. At about nine o’clock on 14 September 1994, something else arrived.

Across Zimbabwe, and over the border in Zambia and Botswana, people looked up and saw a fireball crawling across the sky. Not a shooting star: it took minutes, not seconds. It had a long fiery tail and threw off sparks, and it was flanked by smaller lights that kept station with it. Newspaper switchboards in Harare lit up. Cynthia Hind, the country’s resident UAP investigator, said afterwards that she received dozens of reports describing a capsule with fire behind it and two smaller capsules riding alongside. Some people said they heard explosions.

In Kariba the reports were odder. One woman told the Sunday Mail that a round object with a great many lights had hung over her house at about seven in the evening, silent, and too round to be an aeroplane; her neighbour saw it too. Another resident described a slow, brightly coloured disc that made no sound at all. A charter operator on the lake said it looked at first like a rocket, and then, within a second, plainly was not, because a rocket does not carry a row of green lights. A third man said he saw a ball of fire and assumed it was a comet, and was cross at the suggestion of anything else.

Astronomers in the region said it was a meteor shower. The better answer came later, and is now the standard one: the Zenit-2 rocket that had lofted a Russian military satellite two days before was re-entering the atmosphere on a shallow track across southern Africa, breaking up as it went. A tumbling rocket body does exactly what the witnesses described. It burns for minutes, sheds glowing fragments that seem to fly in formation, and can look, to a person on the ground, as though it is slowing down or hanging still.

That would close the file, except for the calendar. Two mornings later, sixty-two children at a school outside Harare said a silver craft landed beside their playground. Every account of the Ariel School story begins with the Kariba fireball, and every sceptic points out that the whole country had spent two days talking about lights in the sky before the children went out to break. Whether a rocket stage falling over Kariba explains what happened at Ruwa, or merely sets the scene for it, depends entirely on who is telling the story.

Nobody in Kariba found a piece of rocket. The lake is very large, and a lot of things go into it.