People who have witnessed a total solar eclipse know that the awesome spectacle is like no other in nature. For thousands of years, people have been alternately impressed, shocked or terrified by these benign events. Why?
First, it gets dark. All of our lives, we have known that it is daytime when the sun rises and night after the sun sets. This is not true during a solar eclipse. The day starts as bright as any other day. It slowly becomes darker when, suddenly, it is dark in the daytime. But it isn't actually dark, not like at night. Instead, the dark region is surrounded by twilight all around the observer. The sun is blotted out. In it's place is a strange display of light streaming out from a black disk. We know that the light streamers are the solar corona made visible since the intense light of the sun has been blocked. The ancient people didn't know that there was a corona and they could only observe it on the rare solar eclipse times. There was no way for them to determine what was causing it. Various advanced civilizations, such as the Mayans, were able to predict dates on which an eclipse might happen but they couldn't predict where. They certainly couldn't contemplate the solar corona. They also knew that the corona was uniquely patterned during every eclipse. We know that this is caused by solar sunspot activity but it was a complete mystery to the ancient peoples.
Second, total solar eclipses don't last very long and can appear anywhere on Earth. We know that they are caused by the moon passing in front of the sun. Since the moon has a somewhat erratic orbit around the Earth, there are slight differences in the relative position of the moon, Earth and sun each month. Some ancient people realized that the moon was the cause, sometimes, at the New Moon phase. Why didn't such an eclipse happen monthly during every New Moon? If the moon is slightly higher or lower at New Moon, the shadow will be cast into space, missing the Earth completely. Other times the moon's shadow may graze the Earth causing a partial eclipse. These alternate eclipses became known to ancient people through observation but could not be determined in advance. It was only modern astronomers, using calculus, that could accurately predict them with certainty. Now, with the use of computer technology, we can easily determine when and where these events will occur. We also can determine the precise duration of each phase of the eclipse. About the only thing that we cannot determine in advance is the exact look of the solar corona. We can, however, have an estimate. We know the relative solar sunspot activity on the days before the event. This can indicate whether the corona will be large or small.
Third bright stars and planets are often visible during the day. On some occasions, bright comets were detected during an eclipse. Ancient people knew about the stars and may have been able to predict that they would become visible during an eclipse. They were unable to determine where the bright planets, (Venus, Jupiter, Mars and Mercury), would be. The planets have erratic motions that could be observed but not predicted by ancient people. Like the precise calculations made using calculus for eclipses, the calculation of planetary position requires high order math that was unavailable to ancient people.
Finally, the events had an effect on animals, birds and insects just like nightfall did. People were typically not similarly affected. There was a strangeness experienced during an eclipse but people could tell that it was unusual and not like a normal nightfall. As observations were gained, they began to understand that eclipses were always temporary and not to be feared, even if aspects of them were hard to understand.
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Now that we can predict eclipses, there are none that are not witnessed by many who travel just to see the event. There is a wonder to them which can be explained by science but not described. The effects of the eclipse on the animals, birds and insects is amazing to see. The pattern of twilight during the day is amazing to people. The visual sight of the solar corona is best experienced by direct viewing as cameras cannot capture the entire spectacle.
The next total solar eclipse visible from the United States is on August 21, 2017. This is the big one. Millions of people can travel short distances to see it. It starts in Oregon on the coast near Lincoln Beach. It then travels southeast across 13 states. Nashville, TN, is the biggest city to experience the event. Other large cities include Charleston, SC, St. Louis and Kansas City. The latter two, however, are split by the eclipse. What you see will depend on your location.
After that, another eclipse occurs in 2024. The cities of Cape Girardeau, Missouri, and Carbondale, Illinois will both experience these eclipses. It is quite unusual for a single area on Earth to have two total solar eclipses within a time span of under 7 years.
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