The worry is that cloudy weather could spoil the event - or, conversely, that clear skies might tempt people to look directly at the sun. "It's the sun's infra-red rays which do the damage," said Duncan Copp of Mill Hill Observatory in London, "Nobody should look at the sun through any sort of optical instrument such as a telescope or pair of binoculars."
Even looking directly at the sun through improvised filters - like fogged photographic film, smoked-glass or a bin liner - is dangerous, as the heat will quickly burn your retina and damage will be permanent. The only sure way is to view the sun indirectly, through a pinhole camera, or else in a reflection such as a windscreen or puddle.
The most indirect view will be over the Internet, at the Society for Popular Astronomy's World Wide Web page, at http://www.u-net.com/ph/spa/ eclipse/partial.htm. But the society also suggests this alterna-tive pinhole projector.
1) Take an empty cereal packet. 2) Make a small pinhole in one of the shorter sides, a couple of inches from the open top. 3) Point the pinhole towards the sun and look inside the box. A small image of the sun will be cast on to the opposite inside wall.
t On 11 August 1999, people in Devon and Cornwall will see a total eclipse of the sun - the last occurring until 2081.
"The Sky at Night'', the Long Weekend, page 2Reuse content