Total solar eclipse in Shanghai in 2009
Yangtze river eclipse
Total solar eclipse, a magnificent natural phenomenon, has been revered, admired, amazed and appreciated by human beings since ancient times. Since the founding of the People's Republic of China, there have been 65,438 total solar eclipses+September 22, 0968 (the first day of the eighth lunar month, observed in Kashgar and Yining, Xinjiang). ), 65438+February 16 (on the first day of the first lunar month, observed in Ruili, Wan Ding, Yunnan. ) and 16 have been observed in China. On the morning of July 22nd, 2009 (the first day of the sixth lunar month), we will see the most important and longest total solar eclipse in this century in the middle and lower reaches of the Yangtze River in China.
The Yangtze River is the largest, longest and widest river basin in China. Taking Yibin, Sichuan and Yichang, Hubei as the dividing point, the Yangtze River is divided into upper, middle and lower reaches. Since Yibin, it has been called the Yangtze River. Today, the Yangtze River basin concentrates about one third of the country's population and cultivated land, and the total grain output accounts for one third of the country's total output, of which rice production accounts for about 70% of the country's total. During the total solar eclipse on July 22 this year, the total solar eclipse belt traveled eastward along the Yangtze River, and the center line entered the sea in Hangzhou Bay between Shanghai and Ningbo, and entered the Pacific Ocean. Chengdu, Chongqing, Wuhan, Hefei, Hangzhou, Shanghai and many other big cities are in the total solar eclipse zone. Therefore, we call the total solar eclipse in July this year "the total solar eclipse in the Yangtze River in 2009", which should be no exaggeration.
In fact, for this total solar eclipse, the first place observed on the earth is in the coastal area north of Mumbai in western India, where there will be a very rare and peculiar "total solar eclipse sunrise" landscape. After that, the total solar eclipse belt will pass through parts of India, Bhutan and Xizang Autonomous Region, China, then enter northern Myanmar, and then enter China, Yunnan and Sichuan provinces. Chengdu people can start observing the total solar eclipse just after 8 am. Next is the middle and lower reaches of the Yangtze River. Obviously, this is undoubtedly the most densely populated and economically and socially developed area in this eclipse.
Today, with the prosperity of science, many people are familiar with the principle of total solar eclipse. Its basic condition is that the three celestial bodies, the sun, the moon and the earth, run very close to a straight line at a specific moment. Because the orbital plane of the earth and the orbital plane of the moon have an intersection angle, it is difficult to have such an opportunity. Because the total eclipse zone caused by the shadow of the moon on the earth is very narrow, only about 200 kilometers, for a specific place on the earth, the probability of total eclipse will only appear once every 370 years. The longest total eclipse time will not exceed 7 minutes and 40 seconds, with an average of 3 minutes and 30 seconds. This time is also different for different positions on the total solar eclipse belt. The longest duration of this eclipse is 6 minutes and 39 seconds, but the corresponding position is already in the vast Pacific Ocean. In Shanghai and Hangzhou, people can "enjoy" the total lunar eclipse for about 5 to 6 minutes.
At this point, readers may understand why we call this eclipse a "big" eclipse. Most importantly, solar eclipses usually last for a long time. Also, this total solar eclipse zone covers the largest population. In the past, when a total solar eclipse occurred, the total solar eclipse belt often crossed the inaccessible or uninhabited land or sea. This total solar eclipse belt probably covers the largest population in history. No wonder some famous foreign media called this eclipse "the Great Eclipse". Of course, there is still the most important question for this solar eclipse observation, and that is whether the weather at the observation point is good or not. In case of rainy weather, the observation site should be adjusted in time, which is what every observer who is eager to witness the spectacular scene of the total solar eclipse must pay special attention to.
What's the point?
Why does the total solar eclipse attract so much attention from scientists and the public? Generally speaking, there are three reasons:
One is "appreciating nature". Total solar eclipse is a natural phenomenon, and human beings instinctively love nature. Furthermore, human beings have two instincts, one is "love of beauty" and the other is "curiosity". The so-called "love of beauty, everyone has it"; Everyone is curious. The phenomenon of total solar eclipse is magnificent and beautiful. The phenomenon of total solar eclipse is very rare and "strange". For example, in Shanghai, the last total solar eclipse was seen in 1575, that is, during the Wanli period of the Ming Dynasty. The next total solar eclipse will be in 2309. As far as "food machines" are concerned, people who are alive today seem lucky. Therefore, observing the total solar eclipse can greatly satisfy people's curiosity about beauty and express their love for nature.
The second is "experience science". In ancient times, people did not understand the cause of total solar eclipse, let alone predict its occurrence. This cast a mysterious color on the total solar eclipse, and also produced all kinds of stories that looked interesting but far-fetched. To observe the total solar eclipse, people should naturally care about and understand the causes of the solar eclipse and the scientific problems related to solar physics and solar structure. Moreover, the accuracy of the total solar eclipse time forecast given by the computer of the Observatory can be more than seconds. There is no need to make any amendments to relativity and quantum physics here, as long as the results of classical Newtonian mechanics are enough. Today, when the general public looked at their watches, held their breath at the scheduled time and began to enjoy the total solar eclipse comfortably, didn't they also realize the power of science? What is science and what is science?
The third is "research and exploration". In the history of modern science, the special observation during the total solar eclipse made a milestone contribution. On August 1868, French astronomer Janssen observed a total solar eclipse in India. He observed the prominence exposed behind the moon shadow with a spectroscope and found that there was a third spectral line near the two yellow spectral lines corresponding to sodium in the prominence spectrum. It was later confirmed that this spectral line came from a completely unknown element-helium. Lockyer in Britain named it helium, which comes from the Greek word ξλιοs, that is, the sun. 19 15 years, Einstein published his general theory of relativity. However, this innovative theory is difficult to be confirmed by experiments. A corollary of the general theory of relativity is that light will deflect in the gravitational field, for example, when it passes near the sun, it will make the light source "look" move a little. Einstein hopes to verify this prediction by observing the positions of stars near the sun during the total solar eclipse. This idea caught the attention of British astronomer Eddington. On May 29th, 2009, a total solar eclipse occurred in the southern hemisphere. Eddington led an observation team to principe island in the Gulf of Guinea, West Africa, while another observation team from the Royal Astronomical Society went to Sobral, Brazil. The observation results of the two places were published in1919165438+1October 6, which confirmed the correctness of general relativity with measured data for the first time and caused a sensation in the world. The research topics of modern total solar eclipse are mostly concentrated in the field of solar physics, such as coronal inversion, solar magnetic field, solar radio, solar wind, and the influence of the sun on the solar-terrestrial space environment. , as well as neutrinos and gravitational anomalies.
Watch the eclipse carefully
People are often very excited when they see a total solar eclipse, and it is easy to get carried away. But be careful, don't forget that direct observation of the sun will burn your eyes and may even cause permanent damage to your eyes. It is said that Galileo, a scientist, was unfortunately blind in his later years, which was not unrelated to his observation of the sun with a small telescope. Be sure to observe the sun through a qualified and applicable black dimmer. At this point, teachers and parents living inside and outside the eclipse belt must not forget to teach students and children of all ages, especially those who are naive and curious but young and inexperienced. Because, in any case, people's eyes are too precious. In fact, ordinary special dimming tablets for solar eclipse observation are very cheap and can be purchased from specialized institutions. If you want to make it yourself, you should also do it under the guidance of experienced personnel. I hope this point can be widely publicized in the relevant areas of this total solar eclipse.