Four young men in white shirts, a long way from home, on a footpath in the dark. They had walked out that afternoon from Nhlangano to a village on a ridge, two hours down into a valley, across a stream and up the far side, because the villages in that part of Eswatini sit on the high ground away from the floods. They arrived at half past five, and the sun goes at half past six, and none of them was looking forward to the walk back with no torch worth the name and the ordinary African night full of things with teeth.

They left at half past nine. At about half past ten they reached the river crossing at the bottom of the valley. South of the crossing the ground opens out into wide grassland, and beyond it, fifteen or twenty kilometres off, another line of mountains.

One of them said: look at the moon, it looks strange.

The one who wrote the account eleven years later said he answered without looking, because he had already noticed the moon that evening and knew it was in the other direction. Then he looked.

Over the grassland, he wrote, hung a large glowing sphere. It seemed translucent, mostly orange with a little blue in it, and it made no sound whatsoever. The four of them stopped on the path and stared at it. Then, with no warning, it emitted a flash of pure white so bright that the entire valley lit up for a split second, the way a room does when a camera goes off. They could feel, he said, static in the air, and he was careful to add the word literally. The sphere was still there afterwards. About a minute later it flashed again. Then it was gone, and the night was the night again, with the half moon in its proper place and clear sky.

He could not put a size on it. It was far away, near the distant ridge, and its glow reached that ridge, which made it big. The flash appeared to come from its centre. He had never seen weather behave that way, and it vanished too fast, he thought, for a helicopter to have been hovering out there. He asked to remain anonymous, citing his career, and said he had only written because it might be of interest. It was the first thing the four of them had discussed for years.

There is a great deal here that a meteorologist would recognise. A distant thunderstorm below the horizon, in October, over the Lubombo or the Zululand lowveld, throws exactly this: a diffuse orange-pink glow from lightning inside cloud, then sudden, silent, whole-sky flashes with no thunder because the storm is too far off for sound to carry. Ball lightning is a possibility, very rare and never seen at that scale. A flare or a large fire would not flash white and then persist.

Against the storm: the writer said the sky was clear, the sphere had an edge, and it was in one place, low, and then simply not there.

Four witnesses, one valley, two flashes, a static charge nobody could have measured, and a story they carried home and kept for eleven years before telling anyone official. Whatever it was, it waited until they were exactly halfway back, in the dark, at the river.