The Eclipse - 11.11am, 11.8.99: How to See it

THERE IS only one piece of advice that everyone agrees on when it comes to observing an eclipse safely - never look directly at the Sun with the naked eye. To do so risks permanent eye damage and blindness.

Eye doctors are so concerned about the possibility of people losing their sight through looking at the eclipse that they have issued dire warnings about the dangers of even using recommended sun filters.

Professor Liam Donaldson, the Chief Medical Officer and the Government's most senior medical adviser, even went as far as to suggest that people should stay indoors if necessary. "The safest way to view the eclipse outdoors is indirectly with, for example, a pinhole projection viewer. But if you want to enjoy the full effect of this phenomenon use your TV set," he said.

It is not even safe to view the point of total eclipse, according to the Department of Health, although this advice runs counter to just about every expert body in astronomy.

While it is absolutely true that looking at any partial eclipse with the naked eye can, within seconds, cause infra-red radiation to burn the light-sensitive tissues in the retina permanently, astronomers have for many years watched the brief moments of totality without any filters.

The UK Coordinating Group on the solar eclipse - which includes the Royal Astronomical Society and the Particle Physics and Astronomy Research Council - advises that it is possible to view the partially eclipsed Sun directly, provided people use a solar filter made of mylar and marked with the "CE" rating of the British Standards Institution.

"Hold the special filter firmly over both eyes before looking up at the Sun, and don't remove it until after looking away. The Sun should look quite dim and the sky should be completely black - if this is not the case, do not use the filter," the group says.

People in the zone of totality should only remove their solar filters when the Sun is totally eclipsed - but for no longer than the very point when the Sun begins to re-emerge.