Eye experts warn over viewing Sun and Venus

Astronomers and eye specialists are warning against looking directly at the Sun this Tuesday when millions are expected to witness Venus crossing over its face.

Astronomers and eye specialists are warning against looking directly at the Sun this Tuesday when millions are expected to witness Venus crossing over its face.

Robert Walsh of the University of Central Lancashire said the only safe way of watching the transit of Venus is by the indirect method of projecting the sun's image on a screen using a pinhole card.

"The light from the Sun is projected on to a screen, reducing the brightness to safe levels," Dr Walsh said.

Doctors are worried people might peek at the Sun through sunglasses, darkened photographic film or smoked glass, which do not provide enough protection against burning.

A spokesman for the Eyecare Trust, a medical charity, said: "Serious and permanent damage with a real risk of blindness can occur if you look at the Sun with the naked eye, or though a camera or telescope, and children are especially at risk." The trust said the only way of safely looking directly at the Sun is to wear special solar filters.

A full transit - when the planet crosses the entire surface of the Sun during the day - last occurred in 1283. Schools across Britain willwatch the transit by the indirect method, repeating an experiment performed by English astronomer Jeremiah Horrocks, who in 1639 was the first person to predict and see a transit of Venus.

This week's transit will begin at about 6.20am and finish just after midday.