We just viewed our first Solar Eclipse of the year 2010.  As usual, there were many reports of losing the eye sight if you view the eclipse with a naked eye and ways of viewing the eclipse. I didn’t see much of scientific evidence to the above arguments.  Why would I lose my eyesight?  UV rays and other harmful rays are bounced back by ozone layer always.  So, how can it be any different on an eclipse day?

I always believed that those harmful rays always existed.  Only difference is that, you will never be able to see the Sun directly due to its brightness.  This is possible on an eclipse day.  More over, though the light appears not that intense on an eclipse day, its good enough to harm your cornea.  Note that, Cornea doesn’t have any way to sense pain and you will never see when your rods and cones are getting burnt. 

This report from Nasa supports the above argument.  Here are some excerpts. (Thanks to Girish for pointing out to this report)

The only time that the Sun can be viewed safely with the naked eye is during a total eclipse, when the Moon completely covers the disk of the Sun. It is never safe to look at a partial or annular eclipse, or the partial phases of a total solar eclipse, without the proper equipment and techniques. Even when 99% of the Sun’s surface (the photosphere) is obscured during the partial phases of a solar eclipse, the remaining crescent Sun is still intense enough to cause a retinal burn, even though illumination levels are comparable to twilight [Chou, 1981, 1996; Marsh, 1982]. Failure to use proper observing methods may result in permanent eye damage or severe visual loss. This can have important adverse effects on career choices and earning potential, since it has been shown that most individuals who sustain eclipse-related eye injuries are children and young adults [Penner and McNair, 1966; Chou and Krailo, 1981].

There are other Indian superstitions to spice up an Eclipse.  I’ll leave that for another post.