Pupils

Like the diaphragm in the camera, the human eye has a pupil that can be widened or narrowed to measure the amount of light entering the eye. In the dark, dilated pupil diameter of 8 mm in order to collect enough light to allow people to see in the dark. On a sunny day, its diameter shrunk to 2 mm, even able to shrink to about 1.6 mm when faced with blinding light.

But measuring the pupillary light is finite, does not hinder the power of the radiance of the sun was so great. If calculated, direct light from the sun must be attenuated to be 50,000 times safe for the eyes, made the original power of 0.00002. If not, those who dared to challenge the sun is likely to be blind.

Therefore daily glare of the sun radiance is always avoided. But when the eclipse comes, people get interested to observe the sun’s face was turned into a scythe. Scarum was possible, ignorant of the danger.

Because at the time of eclipses, solar radiance partially blocked by the moon so natural to be dim and pupils were dilated. Just as people looked up at the sun, the pupils have not had time to react, when the sun’s surface brightness remains the same fierce with the daily, which shrink in size only to form crescent. It’s certainly an enormous danger that threatened blindness. Even more so when seen through binoculars, camera or other optical instruments are not modified, because there is the lens that focuses light and greatly increases the danger. Do not you ever seen a solar eclipse with the naked eye, especially with binoculars or a camera that is not equipped with a special.

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No need to worry, there are some safe ways to observe the events that once a year does not necessarily stop in the same area. The principle is widely used not see directly but watched the sun’s image on a surface. Like other way, of course the sunny weather is needed. A simple example of the form of cardboard boxes that can be made yourself (see picture).

Field of the width of about 30cm x 30cm were given a small hole (often called a pinhole) diameter of about 1 mm at a distance of 5cm from the edge. Through this hole, the sun will break through to form the image on the surface in the field below. The higher the size of the box, the greater the sun’s image. But for practical, high-box is sufficient if between 50 to 80 cm.

Then on the edge of the hole created as a place wide enough for both eyes to peer into the box. In use, with his back to the sun, holding the box while peering into the eyes.  box tilted a bit to find the best direction that produces the sun’s image in the field below.

Two reasons that make this a safe box. First because a small hole only allows a little glow in the sun. Both because we are observing with his back to the sun, keep the eyes from the spotlight of the sun.

The same principle is also found in other places. Those who could not be prepared to make the box under the tree still get a little sunlight, so that in ordinary circumstances reveal bright dots on the ground. Look at the little dots that, when a solar eclipse to be a sickle shape. If the wind shaking the leaves, bright crescent sickle-it was funny to move around.