Professor Liam Donaldson, the Government's Chief Medical Officer, advised people to stay indoors and watch the event on their television. Yet the Government's official eclipse website, prepared in consultation with the Department of Health, Professor Donaldson's own department, advises that it is safe to watch the eclipse provided people look away immediately the period of totality ends.
Other scientists agreed with the website, claiming that Professor Donaldson was over-cautious, depriving people of a once-in-a-lifetime chance to see one of nature's most amazing spectacles.
Professor Donaldson said there was no safe time to look at the eclipse. He urged people not to look directly at it, nor to wear specially-made glasses or take photographs, as they risked seriously damaging their eyesight.
"To look directly at the Sun at any point of its cycle of eclipse could potentially cause serious damage to your eyesight or even blindness," he said. He advised those who were desperate to see the eclipse to either watch it on television or use a pin-hole projector to view the event.
"The events are going to last a couple of hours and it can take just a split second when the full force of the Sun's rays play on the back of the eye to permanently damage it, and possibly cause blindness," Professor Donaldson said.
"It can affect everyone, particularly children, so I would urge great caution," he added.
However, Dr Richard Wade, a scientist at the Government's Rutherford Appleton Laboratory, speaking on BBC Radio 4, said: "The worrying aspect is the way people will interpret the advice." He added that he feared people would miss out completely on a spectacular phenomenon.
"There is a period, if you are fortunate enough to be under the track of totality, which in Cornwall and Devon will last about two minutes, when it is safe to look at the total eclipse," he said.
"However, the danger is that if you become so transfixed by what really will be a spectacular phenomenon, and you look for too long, and then look at the bright disc of the Sun as it reappears, then there is a really serious danger of damaging your eyesight," Dr Wade added. His advice echoes that of the Government's official website.
Nigel Henbest, The Independent's astronomy columnist, said that eclipses are not dangerous as long as people take the right precautions. "Eclipse shades", made of mylar film which blocks dangerous radiation, will be in plentiful supply as the big day approaches, he said. "Always view the Sun through these during the partial phases and for the entire eclipse if you're in a place where it's not total. Then, when totality strikes, whip them off. You'll know it's totality, because everyone around you will be whooping and yelling and clapping."
But Professor Donaldson said: "It isn't safe to use any sort of screen for your eyes to look at the Sun during the eclipse. Experience the atmosphere outside and then pop indoors and watch it on television." Weather forecasters have predicted the eclipse could be affected by cloud on 11 August, but Professor Donaldson said this did not necessarily lessen the danger.
Thousands of people are expected to travel to the south-west of England on 11 August to view the first total eclipse of the Sun in Britain for 72 years. In other parts of the country people will be able to see 80 or 90 per cent of the eclipse. Although the event will last for two and a half hours, totality, when the Moon covers the Sun, will last only a couple of minutes.Reuse content