Nasa: Eye Safety During Solar Eclipses

This resource, which is provided for by NASA, gives great information on protecting your eyes during solar eclipses. Your eyes are very difficult to replace. Even when 99% of the Sun's surface is obscured during the partial phases of a total eclipse, the remaining photospheric crescent is intensely bright and cannot be viewed safely without eye protection. Do not attempt to observe the partial or annular phases of any eclipse with the naked eye. Failure to use appropriate filtration may result in permanent eye damage or blindness!