Just before four on a Sunday morning in midwinter, a woman in Phoenix, the big suburb on the hills north of Durban, is awake when she should not be, and looks out of the window.

There is something in the sky. She told the Daily News that week that it was a massive ball of light, much brighter than the sun, with blue and purple colours running through it. It pulsed. As she watched, it changed its shape, going from round to oval and back again. Her first thought was a police helicopter, which is a very Durban first thought, but a helicopter makes a noise and this made none.

She woke her husband. He was not, by her account, delighted to be woken, and said so. Then he looked, and got up, and found the video camera. Their daughter refused to get out of bed at all, which is the most believable detail in the story.

The couple filmed the thing, on and off, for the best part of three hours. It did not go anywhere. It hung in the same part of the sky, pulsing and changing shape, until the light came up over the Indian Ocean and it faded into the dawn. Then it was gone, and by breakfast time they had a tape and no idea what was on it.

The Daily News did the reasonable thing and rang the weather office. A forecaster there ruled out a weather balloon: the balloons go up at midnight and midday, he said, and stay up two hours at most, so nothing of theirs was in the sky at four and still there at seven. The couple asked, through the paper, for anyone who could analyse their footage to get in touch. Nobody who did has ever said what they found.

The dry footnote, which the Wikipedia list of South African sightings supplies, is that at least one later commentator suggested the planet Venus.

That is worth taking seriously, because the calendar is on its side. On 8 June 2004 Venus had crossed the face of the sun in a transit that half the world watched with cardboard glasses. Three weeks later it had swung out to the other side and become a blazing morning star, rising in the east and climbing until the sun washed it out. It is, at that point in its cycle, the brightest thing in the sky after the moon, and low down over a humid city it shimmers, flares, splits into colours, and, to an eye with nothing to compare it against, visibly changes shape. A video camera on full zoom turns it into a wobbling, pulsing, oval blob. It is silent. It does not move for hours. It disappears exactly at sunrise.

So the sceptic’s case is tidy, with one snag. From Durban on that particular morning Venus came up at about ten to five, and the couple put the start of their sighting at just before four. Either the clock in the story is loose by an hour, which happens, or they were looking at something else for the first hour and Venus for the rest, or it was not Venus. Nobody from the paper stood in that garden at four in the morning and pointed, and the couple saw something far brighter than they expected a planet to be, and said so.

The tape, so far as the archive can tell, is still somewhere in Phoenix.