Ref. 30772-47STARGAZERS have been warned not to risk their sight watching a rare astronomical event tomorrow. From around 6am, the planet Venus will appear as a small black dot passing across the bottom of the sun.

Britons last witnessed the event in 1882 before the days of sophisticated cameras and telescopes.

But those planning to dig out their binoculars are urged to think twice.

Paul Compton of Gorse Hill opticians Haine & Smith, said looking at the sun for even a few seconds, without the proper equipment, could lead to blindness.

"The main concern is Solar Maculopathy, which is the burning of the retina," he said.

"There are varying degrees with the worse case scenario being blindness."

And Mr Compton, who has 10 years' experience, warned sunglasses would give little protection against the sun's harmful rays.

He said: "The average pair of sunglasses reduces glare by cutting out ultra-violet rays.

"But it's the infrared radiation that does the damage."

Amateur astronomer and photographer Philip Perkins, of Ramsbury, near Swindon, plans to use two telescopes with special filters to provide a live webcast, enabling people to view the event safely from the comfort of their home or office.

He said: "No living person has ever seen this event so it's extremely exciting.

"In order to get a decent view, some form of magnification will be needed.

"This may tempt some to use their binoculars, but this is very dangerous. Within a split second you could become blind."

The Government's Chief Medical Officer, Sir Liam Donaldson, has also appealed for caution.

He said: "We want viewers to enjoy it safely. Children are particularly vulnerable as they will be tempted to take a peek we must do all we can to protect their eyesight.

"Under no circumstances should people look at this event directly. The risks to sight from looking at the sun are very real and could lead to irreversible damage and even blindness."

The transit will begin at about 6am and continue until noon.

The website link can be found at www.astrocruise .com/venus_transit.htm.

l In August 1999 the skies above Swindon were darkened during a total solar eclipse. Staff at the former Princess Margaret Hospital were put on standby to deal with expected cases of eye damage.

Fortunately, cloud cover prevented the most serious cases.

Elsewhere in the UK, however, hospitals were inundated by hundreds of people who ignored the warnings.

Kevin Shoesmith