One of nature's most intriguing shows is the solar eclipse. For centuries, when man did not yet know how to explain the occurrence of certain natural events, the eclipse aroused fear, respect and raised broad questions. The ancient astronomers, mostly priests, associated the event with deadly times, since the Sun was often interpreted as a divinity. The eclipse then did not happen cyclically at regular intervals and it was not possible to predict it, with the knowledge of that time, which increased the feeling of unease and terror.
The explanation of the eclipse today we know is quite simple. But the eclipse occurs through a miracle of nature, an accidental coincidence due to the proportion between Sun and Moon and the distance of the Sun from us observers.
First of all, let us analyse what an eclipse is and why it occurs. Eclipse occurs when one celestial body is partially or totally obscured by another. This means that there is not only the solar or lunar eclipse, but also eclipses between various planets that at the appropriate distance can obscure bodies that are located "behind" from the observer's perspective. For us Earthlings, the most frequent and easily observable eclipses are the lunar and the solar eclipses. The second is the most spectacular. The eclipse of the moon occurs when the Earth interposes between the Sun and the Moon: in this case it is the shadow of our planet that projects onto the Moon with the classic shadow cone (the cone is the geometric figure formed by the shadow of a spherical body like our planet). The eclipse of the sun, such as that which occurred yesterday August 21 and was visible in most of the United States of America, instead occurs when the Moon interposes itself between our planet and the Sun. In this case, the Moon projects its shadow onto Earth, creating the darkness (which does not happen due to the darkening of the Sun by the Moon, which is infinitely smaller, but precisely because of the shadow: exactly as it happens on earth, when we put the beach umbrella in the beach that projects its shadow creating conditions of small darkness).
The solar eclipses are very spectacular because the Moon darkens the Sun. When the eclipse is total, we can clearly see the solar crown, so much so that in a very short time we pass from a day to a night situation. The temperature is lowered and the darkness stretches along the entire territory of the apparent path carried out by the Moon in that period of time.
The total eclipse is possible, we said above, for an extraordinary coincidence: the Moon has a perfect measure for it to fit inside the solar disc. In fact, the Sun has a diameter 400 times greater than the Moon's diameter, but it is also 400 times further away from us. So this relationship between distance and greatness, makes us see the Moon perfectly embedded in the Sun, when the eclipse occurs. This coincidence is very rare, the total eclipses between other celestial bodies in the Solar System are not possible due to the lack of relationship between distance and magnitude. At the peak of the eclipse, the Moon completely covers the Sun except its crown. Astronomers from all over the world, equipped with instruments suitable for observing our star, can clearly see the crown erupting coronary mass, which gives rise to the solar wind. Through a total eclipse it was possible to confirm with facts Einstein's theory of relativity, which for years had remained a mere unconfirmed hypothesis.
The visibility of the eclipse depends on the path that makes the Moon's shadow on our planet, but it is a very narrow band, not more than 200 kilometers wide. Outside this band, only partial eclipses will be seen (through the penumbra).