A total solar eclipse occurred on July 22, 2009 after many days. We are very lucky that the people of this country could see it clearly from Panchagarh area of Bangladesh. The next one will be seen more than a century later – so this solar eclipse can undoubtedly be considered a major event in the country's history.
We now know that when the moon appears directly in front of the sun, the sun is covered, we call it a solar eclipse. We are very fortunate that our moon is roughly the right size and orbits at the right distance. If it had been smaller or had a larger orbit, it would never have completely covered the Sun and humans on Earth would never have seen a total solar eclipse.
When people did not know exactly what caused a solar eclipse, it is not surprising that there was a kind of panic among them. People can feel panic when the sun suddenly goes out in the midst of the bright light of the day. Still many people of the world continue to pray in various forms of worship until the eclipse ends! People heave a sigh of relief when the sun moves out from behind the obscuring moon and the light shines again.
After knowing why solar eclipses happen, the people of the world are less anxious and can enjoy the beauty of the spectacular phenomenon when a total solar eclipse occurs.
The sun is so bright that if there is not a total solar eclipse, if even a small part of it remains visible, then the beauty of the total solar eclipse cannot be seen. The Sun is surrounded by a band of bright light, actually a ring of hydrogen atoms hotter than the Sun over millions of kilometers – called the corona, and from this corona radiates such light that humans on Earth can see it with the naked eye only during a solar eclipse (Fig. 30.1).
Another phenomenal thing happens during a total solar eclipse, when the stars suddenly become visible in the sky during full daylight. There is not much more amazing thing in the world.
Stargazing during a total solar eclipse is an unprecedented sight on Earth today, but it was once one of the world's most important scientific experiments.
Einstein published his special theory of relativity in 1905. As soon as he published the Special Theory of Relativity, he started working on the General Theory of Relativity. Now we all know that this General Theory of Relativity is the correct explanation of the gravitational force but at that time scientists on Earth were not willing to accept it. Earlier Newton's formula for gravitational force could explain everything from the rotation of the moon, sun, and planets in the solar system for two centuries to the motion of an apple falling from a tree on Earth.
No one knew that a new formula for gravity was needed. Newton's law could explain everything about gravity—only a very small deviation in Mercury's orbit could not explain it. (The deviation was so small that it was unbelievable that scientists bothered about it! Mercury's orbit would deviate by one-sixth of a degree in a hundred years.) Scientists thought that there might be a planet they hadn't seen, the pull of which caused this deviation in Mercury's orbit. happening
Einstein explained this deviation of Mercury's orbit with his General Theory of Relativity, but established scientists on Earth did not pay much attention to it. No one was very keen to throw away the highly successful space formula of a great scientist like Newton and accept a strange formula combining position and space time of a younger unknown scientist named Einstein.
Einstein was suffering from a kind of restlessness, he then realized one thing. He cannot convince the scientists by explaining the old problems of the earth, if he makes a prediction and if that prediction matches letter by letter then maybe the scientists will believe his general theory of relativity. Einstein then thought of a surprising experiment. We generally know that light travels in straight lines.
But due to the huge mass of the sun, the space around it will become curved, because of that curved space, when the light goes straight, the light will become curved. (Fig. 30.2) To perform this experiment, the light from the star will be bent by the Sun. But there is a serious problem with this experiment, the Sun is so bright that it is out of the question to see stars in its vicinity due to its blinding light. Einstein realized that there was only one way to do this experiment, and that was to look at the lights of the stars passing by the Sun during a total solar eclipse. Einstein calculated exactly how much the light of the star will bend when passing by the Sun.
Now this experiment requires a total solar eclipse – but the problem is that solar eclipses cannot be made at will. Einstein checked the calendar and saw that there would be a total solar eclipse on August 21, 1914 in Crimea, Russia. Irwin Freundich, a scientist friend of Einstein's, decided to go to Russia to photograph the stars during a solar eclipse.
The expedition was a prime example of what accidents can happen in the lives of scientists. Just then World War I is about to break out and Germany declares war on Russia just as scientist Irwin Freundich is roaming Russia with his telescope cameras and equipment! Russian police arrested him on suspicion of spying and in this famous scientific prison while a total solar eclipse was taking place in Crimea.
Irwin Freonditch's forehead is good, coincidentally, at the same time some Russian officers were arrested in Germany and he was released in a prisoner of war exchange between the two countries!
It is needless to say that Einstein was very disappointed when the first experiment to measure the deviation of the position of the stars during the solar eclipse went in vain. He checked the calendar again and discovered that the next total solar eclipse would be on May 29, 1919, and would be visible from South America and Central Africa. Arthur Eddington of the Cambridge Observatory was the most suitable person to carry out this delicate experiment by photographing stars during eclipses.
But he got into trouble, the war was on and the British government decided to send him to war. Eddington will not participate in the war for ethical reasons but the government will send him to fight – eventually more scientists save him from the war and Eddington sails to Africa to photograph the solar eclipse!
Earth scientists have done many delicate and complex experiments in the laboratory, but this experiment is completely different! For this, scientists have to completely depend on nature. Solar eclipses begin slowly and last for several hours, but total eclipses last only a few minutes.
If for some reason the clouds come and cover the sun in those few minutes, scientists may have to wait another century! Eddington made all preparations with his team and the dark clouds that came just before the eclipse covered the sky. Not only that, a heavy storm started with lightning. It is not difficult to imagine the extent of the scientists' disappointment.
But they discovered that just before the total eclipse, the sky began to clear and the sun began to peek through the clouds. Without once looking up at the sky, Eddington began taking photographs with his colleagues and took sixteen photographs during the 302 seconds of the total eclipse. After developing the photographs, it turned out that there was only one image that could be used in this amazing scientific experiment! That too was analyzed and it was found that Einstein's predictions were literally true. Starlight is bent exactly as it is supposed to be when it passes by the Sun.
The results of that famous experiment were published on November 6, 1919, and a young scientist named Einstein immediately became a "superstar" in the world of science!
He is still a superstar in the world of science and will remain a superstar for as long as civilization on earth survives.
