On August 21st, a significant part of Americans will witness a total solar eclipse, also known as the Great American Eclipse. It will be the result of the moon passing right between the Earth and the sun, producing a shadow in some regions of the world.
It would be the first total solar eclipse that passes from the West to the East side of America in almost a century. Some expect it to be a life-changing experience.
However, there are a lot of things people need to know about this type of events, for example, scientists recommend people to avoid looking directly at the sun to admire this phenomenon.
A once-in-a-lifetime experience
A total solar eclipse occurs when the moon passes between the Sun and the Earth, blocking the rays of the sun. Everything goes abruptly dark when this happens, even in the middle of the day. It is certainly a rare experience that not enough people get to see in their lifetime. For example, not a single solar eclipse has been observed in St. Louis since 1442, and the next time a total solar eclipse will be visible is in 2505, according to scientific appraisals.
Therefore, people from both the east and west coast wouldn’t want to miss an event that hasn’t happened in almost a century – since 1918- in the United States, having this opportunity on August 21st. Several cities will be completely dark for two to three minutes thanks to the eclipse since they are in the path of totality of the eclipse, which is the part of the earth facing the moon as it covers the sun. Viewers will be able to watch planets and stars while this happens. It will be visible along a narrow path from Oregon to South Carolina, people outside this route will be able to admire a partial solar eclipse.
Total solar eclipses are rare
The sun is about 400 times larger than the moon, it is also way farther than the moon, so technically, it wouldn’t be that hard for them to align at some point, creating a solar eclipse. However, these are not seen that often from the Earth, and it is because there are a lot of factors to consider. The moon’s orbital shape is elliptical, not circular, so its distance from the Earth is not always the same. Sometimes when the moon passes between the Earth and the sun, it doesn’t produce that shadow on the earth.
Another factor is the moon’s inclined orbit relative to our planet’s equator. Because of this, most of the times when the moon eclipses the sun are not visible from the Earth. In these cases, the shadow of the moon projects below or above the earth.
About 70 percent of eclipses are not visible from planet Earth, but even supposing that the distance and the inclination of the moon are perfect, there is another thing that might not let people observe solar eclipses is the fact that most of the earth is made up of water.
Only a third of the earth is land. Consequently, many times when total solar eclipses are seen from the earth, they are visible only from the oceans, where not a lot of people are going to admire them. As well, it is important to consider the condition of the sky because when the sky is full of clouds, eclipses are harder to see.
Directly watching the eclipse can cause eye damage
Given the rarity of this phenomenon, scientists recommend people to take a chance to admire such a remarkable and unique experience. However, experts recommend people not to look directly at the sun with the naked eye because it can cause serious consequences – leading to irreversible eye damages-, even if the sun is 93 million miles away from the Earth. They recommend people to use the right eye protection.
“Even very short direct observation of the sun has the potential to cause damage,” said Dr. Russell Van Gelder, a clinical spokesman for the American Academy of Ophthalmology (AAO) and director of the University of Washington Medicine Eye Institute in Seattle. “If you take a lens that has that much power and point it directly at the sun, the energy becomes very high”
Gelder said that watching the sun with the naked eye is actually enough to burn holes in the retina or in the light-sensitive cells at the back of the eye. This damage affects the fovea, which is responsible for a sharp, central vision, causing a condition called retinopathy.
Some patients can recover from retinopathy, but many times the damages are permanent. According to a study, out of 15 patients who were diagnosed with retinopathy after having seen the eclipse of 1999 in England, two had permanent damages. Sometimes the people can go blind just for staring at the sun for a while.
Source: Scientific American