"THESE ARE hardened professional astronomers who are cynics to the core, and to see their reaction was a surprise," said Jasper Wall, Visiting Professor of Astronomy at Oxford University. "I didn't think they'd give a hoot, they had seen it all before and yet they were moved. I had been told that this would be the single most moving physical thing you'll ever see in your life. I can go along with that."

For the 250 astronomers and their families, who had gathered on the battlements of Fort Albert on the island of Alderney the thin layer of mottled cloud, which had threatened to hinder the first total eclipse in 72 years, simply served to provide a dramatic backdrop to the events of the morning.

First contact - the instant when the Moon kisses the Sun - had come at 9.59am without being noticed, thanks to the bank of hazy alto-cumulus cloud at 7,000 feet. The next clear view was at 10.23am when a break in the clouds revealed that a sixth of the Sun had now been swallowed up. A further 20 minutes passed behind a screen of cloud, providing an occasional, tantalising glimpse of a crescent-shaped Sun now impersonating a waxing Moon.

At 10.50am the Sun had metamorphosed into a pair of bull's horns. Such were the optical illusions created by the movements of a lump of dead rock 240,000 miles away as it veered in front of a huge nuclear furnace 93 million miles from the Earth.

Then it began in earnest. We were suddenly aware of the cold as the Sun's heat evaporated away, fading at an unimaginable speed. A ghostly twilight grew rapidly in intensity as people shivered with the cold.

Total solar eclipses can only occur because of the chance coincidence of the Sun being 400 times further away from the Moon than the Moon is from the Earth. And yet the Sun is precisely 400 times bigger in diameter. If the Moon was any nearer or further away its disc would not so perfectly obliterate the disc of the Sun.

The clear distinct edge of the Moon when seen during the partial phase of a total solar eclipse is the result of our only satellite having no atmosphere. A lunar eclipse is by comparison fuzzy at the edges of the Earth's shadow, because of our planet's atmosphere.

At 11.04am the thinning cloud gave another view of a bright fingernail of light, and nearby sandpipers stopped their singing. Five minutes later - about 98 per cent totality - and the colours of the surrounding stone buildings began to take on an unnatural hue.

A minute before totality - 11.14am - and it happened. Over Alderney's Braye Bay to the west a black shadow loomed over the horizon. This was the Moon's shadow of totality, the umbra, which was travelling at up to twice the speed of sound as it crossed the globe from Nova Scotia to the Bay of Bengal. We saw the final diamond ring of the Sun disappear behind the lunar disc. Clouds obscured the view for a few more seconds. Then, to the sound of startled gasps, we witnessed the glowing corona of the Sun as it caressed the full, round outline of the Moon. This was the moment of totality when for two, long minutes our physical contact with the Sun seemed to be lost for ever.

Blackness was all above us yet around the entire horizon we could see the strange glow of a far-off day. The umbra had for that brief moment decided to part itself over our small corner of the world.

Then, with a dramatic twinkling of a diamond ring as rays of sunshine shone through the deep valleys of the Moon, the Sun reappeared. This time we cheered spontaneously. Just as quickly as night had arrived, the blackness disappeared. As it continued to move east, we felt the return of daylight as it rushed in from the west.

Professor Michael Rowan Robinson, an astronomer at Imperial College, London, said he felt humbled by something he had known about from reports but had not until yesterday experienced. "It is not so much an astronomical thing, as a human thing," he said.

Ian Williams, Professor of Astronomy at Queen Mary's College, London, found it difficult to come to terms with yesterday's total eclipse, despite his knowledge of what had happened. "Everything happened as we had been told it would, but it was still unbelievable."

Jackie Mitton, an astronomer with the Royal Astronomical Society, said she felt "weak at the knees". She had seen a previous total eclipse in a cloudless sky but this was so different. "The quality of light was so strange. It was a completely different experience," she said.