Eye Safety During Solar Eclipse

Solar eclipse is considered as one of the most fascinating things in nature. People love to enjoy such strange events in which occur in our mighty universe. This astronomical event is even valuable for scientists, students and professional photographers. You might know the important contribution of solar eclipse in formulating the Einstein's theory of relativity. He has been waiting anxiously for a solar eclipse for many months to study the slight bending of light from stars due to solar gravity.

Direct viewing of sun during solar eclipse

Why it is un advisable to look at solar eclipse with naked eyes? As we all know that it is harmful to look at the bright sun. It is because sun light contains some high intensity wavelengths like ultra Violet(UV) and infra red which can affect the retina. Continuous exposure of the light sensitive retina to intense light damages the light sensitive rod and con cells. This light triggers certain chemical reactions which disable the cells to respond to visual stimulus. Over exposure of high intensity light can also permanently damage the photo sensitive cells and can cause a permanent blindness. This is caused by a solar injury, the high intensity light literally cooks the cells and creates a permanent damage. Also our eye is not designed in a way to bear the overall light intensity of bright sun.

 When it comes to solar eclipse, there are some serious warnings from astronomers and physicists. Clear questions can be raised in this case, because during the solar eclipse the intensity of sunlight is highly reduced and as a result the damaging effect must be minimum. Instead it is advised to be more careful during solar eclipse. The reason behind is firstly some amount of infra red and ultra Violet rays may still be coming from the small glaring portions of the sun. The radiations when fall directly on the retina can have damaging effects. Secondly, when we look at a dark area the aperture of our pupil automatically expands to let enough light to enter. In the same way when we look at the solar eclipse, the aperture expands to allow maximum light to pass through it, as the eclipse don't take any longer time, a beam of bright sunlight may suddenly fall. In such a case enough light will have been already fallen on the retina before aperture limits the amount of light. In other words, the sun may surprise us by suddenly throwing it's first beam of light during the eclipse.

Safety measures

According to a NASA report, which says "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."

To view the sun directly during a solar eclipse is safe only when solar filters are used. These filters always have a thin layer of chromium alloy or aluminium deposited on their surfaces which attenuates both visible and infra red radiations. One of the most widely available filters is a welder's glass which can easily be obtained from a welder supply store. Another cheap alternative is aluminized Mylar used mostly for solar observations.Your eye is your World, protect this priceless gift of God.