Why Do We Need Special Glasses to Watch the Eclipse? 

"The eclipse will be visible from most parts in the country from 9 a.m. to 12 a.m. tomorrow. Experts remind that viewers need to wear special glasses to avoid eye damage when watching the eclipse."

"Mom, we've seen this news several times. I want to watch the eclipse and I have to buy glasses!” Mackle pestered Mom to take him to watch the eclipse. It was a once-in-a-lifetime opportunity.

"Mom has got things to do tomorrow. Didn't I tell you? If you want to go, go with Mrs. Lee and her kids."

"Ok, but Mom, I want to buy glasses. Can you buy me glasses? It's too late to buy online, let's go to the shop."

"Why wear glasses? I don't quite understand. Would you like to tell me about it?"

Mackle had become the 'encyclopedia' in the family. He could seem to answer anything his families failed to understand.

"Ok, Mom, I'm telling you. If you want to watch the eclipse, you have to wear glasses to protect your eyes. Usually, we don't stare at the sun for a long time, so we can't notice the harm of looking directly at the sun. But the sun does not only produce visible light rays, but also a lot of high-energy ultraviolet and infrared rays. These ultraviolet and infrared rays can hurt and even blind our eyes!

If you stare at the sun for a long time, the light it produced will burn the outermost layer of your eyes, namely the cornea. This can cause pain and inflammation in the eyes, which is medically known as "photokeratitis". In addition, a large amounts of strong light rays can damage proteins in the crystalline lens. Serious protein damages will lead the lens to go wrong and cause cataracts, blurring the vision. Moreover, the worst is that the strong light can hurt photoreceptor cells in the retina. It is these cells that give the retina a clear picture of the world for us to see clearly. If your photoreceptor cells are damaged by bright light, you will suffer 'solar retinopathy'. This can cause temporary or even permanent blindness.

We will not stare directly into the sun. But when an eclipse occurs, we are curious and want to watch it. We may forget to protect our eyes because the strong light is seemingly 'blocked' by the eclipse, but it's still there. We think it will do no harm to our eyes, but it does burn our eyes. Therefore, it's a must to wear special glasses to watch the eclipse!"

"Ah, I see. Here, wear these tomorrow," Mom gave a pair of glasses to Mackle. In fact, she had already known that there would be an eclipse tomorrow and Mackle would not miss this opportunity. So she was careful enough to learn about eclipse and buy the glasses in advance. With such a surprise, Mackle exclaimed, "Wow, thank you, Mom! I'll take pictures for you tomorrow."

"So sorry I can't be with you tomorrow. But have fun with Mrs. Lee and her kids," Mom smiled at Mackle, who was playing with his new equipment, and felt happy from the heart.

Author: Zhu Yawen