Cloudy outlook for first solar eclipse in 10 years: Best views predicted in east - Eye specialists warn of hazards

Susan Watts,Science Correspondent
Monday 09 May 1994 23:02 BST
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ONLY THE lucky few will catch sight of this evening's eclipse of the Sun - the first visible from Britain for 10 years.

Cloudy skies threaten to mar the astronomical display, due between just after 6.30pm and 8.30pm. The Moon will pass between the Earth and the Sun, blotting out the Sun's surface - about half will disappear from view at the climax at about 7.30pm.

Observers in the east should get the best show - clouds are expected from the west. The London Weather Centre is cautious: 'I don't think many people are going to see it,' a spokesman said.

Eye specialists also warned amateur astronomers to take care. The slightest glimpse of the Sun with the naked eye can cause permanent damage. Children are at greatest risk because their pupils open wider.

Observers should not watch the eclipse directly, even through sunglasses or filters, and certainly not through binoculars or telescopes. The Sun may not appear to dazzle but its invisible infrared and ultraviolet rays are harmful. In 1984, after a similar eclipse, 11 people needed treatment for eye damage in Manchester alone.

It is best to project the Sun's image onto a piece of white card, either through binoculars with one lens capped off or through a pinhole in a piece of card.

Tonight's eclipse will be only partial, and 'annular', with the Moon leaving a thin ring of the Sun's surface exposed. The event is unusual in that it will be seen across a broad swathe of the Earth's surface, although the ring itself will be visible only from the US and Canada. From Britain, the Moon will encroach onto the Sun's face from roughly the four o'clock position.

Eclipses occur when the Earth, Sun and Moon line up. By coincidence, the discs of the Sun and the Moon appear roughly the same size in the sky; the Sun is in fact 400 times bigger, but is also 400 times further away.

During a solar eclipse, the Moon physically passes between the Earth and the Sun, blotting out its light. In a lunar eclipse, the Earth passes between the Sun and the Moon, creating a shadow over the Moon's surface.

Eclipses of both types are relatively common. There are at least two eclipses of the Sun every year, but most pass unnoticed because so much of the Earth's surface is uninhabited.

Ten years is the longest period Britain has gone without seeing a solar eclipse (except for a minor one visible only from Scotland last year) for more than 2,000 years - usually these occur every couple of years.

Eclipses have been known to strike fear into the hearts of observers and to prompt strange behaviour. Patrick Moore recounts in the Guinness Book of Astronomy that in 1980 the cricketing authorities called a rest day when an eclipse fell during a match between England and India, fearful at the risk of members of the 50,000-strong crowd blinding themselves.

In two weeks, on 25 May, the Moon will be partially eclipsed, but visible only in south-western Europe. The next total eclipse of the Sun in Britain is due in August 1999 - the first since 1927. However, this will be total only if viewed from Cornwall.

(Graphics omitted)

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