Why can't we look directly at the sun?

Experts report that you cannot look directly into the sun without proper protective equipment.

According to ScientificAmerican, it is because the sun is 93 million miles (or 150 million kilometers) away from us, but it can still cause serious eye damage, even irreversible damage.

Looking directly at the sun can cause eye damage.

Dr. Russell Van Gelde, a spokesperson for American Academy of Ophthalmology (AAO) and director of the Eye Institute at the University of Washington, in Seattle said: "Even just watching the sun for a moment can causing eye damage ".

On August 21, 2017, the Moon will be in the position between the Sun and Earth to create a total and total eclipse phenomenon in many parts of the United States. This will be the first time since 1918 the total solar eclipse will be seen across the United States (from the west coast to the east). This information is endorsed by the American Astronomical Society (AAS). In addition to areas where total eclipses occur, other places will see the sun partially obstructed.

No matter where you observe the solar eclipse, the most important thing is that you cannot look directly at the sun with the naked eye. To understand later, imagine a children's game using a magnifying glass to focus energy from sunlight and create a hole in the paper.

Focusing the sun's rays on a single point creates a lot of energy.

Van Gelder said: " Focusing the sun's rays on a single point creates a lot of energy ." And the lens in your eyes is four times stronger than the magnifying glass that young children often play.

He continued: "If you have a lens with a high ability to focus and direct it directly into the sun, energy will become very large" , enough to burn burns literally or light-sensitive cells. on the back of the eye.

Patients with this condition are often called retinopathy (retinopathy can be caused by many other causes) - when the eye has been damaged by light rays from the sun. Injury occurs when photons (light particles) produce free radicals and it can kill cells. Damage occurs in the eye hole, a position in the retina responsible for sharpness, which is the center of vision. As a result, sunlight-induced retinopathy can blur the vision or cause blind spots in the eyes.

Many patients have retinopathy because solar energy can recover on their own, but some suffer from long-term vision. For example, in a 2002 study with 15 patients with solar retinopathy in the UK due to a solar eclipse in 1999, only two of them had normal vision when tested from 8 to 12 months later. Some have a normal eye and the other eye has a small blind spot that affects vision.

In theory, a person can become blind - vision only reaches 20/200 or worse - after staring at the sun. But staring at the sun cannot lead to complete blindness because solar retinopathy doesn't affect peripheral vision.

Want to look at the sun, remember to use protective equipment.

Because of the dangers, AAO recommends that people should never look directly at the sun. There is an exception to this rule - if you are in the path of a total solar eclipse, you can look directly at the sun with your naked eye for a short time , meaning your vision is obscured. by the moon. (The full length will vary depending on where you see the eclipse, but at least, the event will last about 2 minutes and 40 seconds).

But there is a way to view total eclipse safely, use a special "solar eclipse" or portable solar filter (even with a partial eclipse. or look at the normal sun). The following four manufacturers have been certified for portable "solar glasses" and portable solar screening devices: Rainbow Symphony, American Paper Optics, Thousand Oaks Optical and TSE 17.

Again, remember never to look at the sun through a camera that doesn't filter sunlight, telescopes or binoculars, regardless of whether you're wearing eclipse glasses. Because these devices will focus the sun's rays even more strongly than what your eyes can do, this will lead to serious eye damage.