– Ed
A solar eclipse occurs when the moon passes between earth and the sun, thereby totally or partly obscuring the image of the sun for a viewer on earth. A total solar eclipse occurs when the moon’s apparent diameter is larger than the sun’s, blocking all direct sunlight, turning day into darkness.
The solar eclipse of August 21, 2017, was visible within a band across the entire contiguous United States passing from the Pacific to the Atlantic coasts. Whilst there was much excitement surrounding this event, there is also a very real danger of incurring permanent damage to the retina, resulting in serious visual impairment.
In every day life, the brightness of the sun in itself is a safety measure for earthlings, because it is difficult to look at it even for a fraction of a second. When there is an eclipse, the rays are far less intense and allows one to gaze at it for a longer period of time. The problem is, high energy rays are still shooting out at your eyes. The effect is best compared with the situation when using a magnifying glass to focus the sun rays onto a piece of paper, which, after a short while will start burning.
The cornea and the lens of the eye focus the light rays onto the retina and they come to the strongest focus at the center of your retina, in an area called the macula, which is where your best vision comes from. It’s the only spot in the retina that’s capable giving us 6/6 vision.”
When looking directly at an eclipse, so much light energy is still focused onto the retina, that it creates heat and can burn a hole in the retina. This can cause irreversible damage with devastating effects on functional vision.
Ordinary sunglasses cannot provide adequate protection when looking at an eclipse. You need special eclipse glasses that can block out much, much more light that ordinary sunglasses.
Even special eclipse glasses are not adequate enough when viewing an eclipse through binoculars or a telescope. These devices require their own special filters to be considered safe.
Moreover, makeshift devices like film negatives or smoked glass can be very dangerous. Stealing quick glances at an eclipse will still be just as dangerous.
The bottom line is, viewing an eclipse without adequate protection can very harmful to our eyes and cause irreversible damage.