On July 22nd, 2009, a spectacular total solar eclipse occurred in China. The total lunar eclipse belt passes through many places in China, and the observed total lunar eclipse time is the longest.

] Basic knowledge of total solar eclipse

The process of total solar eclipse can include the following five periods: initial loss, eclipse, eclipse, luminescence and last contact.

Explanation of total solar eclipse

Since the moon orbits the earth from west to east, an eclipse always begins at the western edge of the sun's circular surface. When the eastern edge of the moon just touches the round surface of the sun (that is, when the eastern edge of the moon is tangent to the western edge of the sun), it is called the initial loss. The first loss is the moment when the eclipse begins.

The eclipse begins with the initial loss, that is, the partial eclipse stage. The moon continues to move eastward, the part of the sun's circular surface covered by the moon gradually increases, and the intensity and heat of sunlight are obviously reduced. When the eastern edge of the moon surface is inscribed with the eastern edge of the sun surface, it is called eclipse. At this time, the entire circular surface of the sun is covered, so the solar eclipse is the moment when the total solar eclipse begins.

1. eclipse law

Eclipses occur up to five times a year. If it appears five times, it must be a partial solar eclipse. There are at least two eclipses on the earth every year. Only partial solar eclipse can be seen in the polar regions. Total solar eclipse occurs every 1 year and a half. Every eclipse starts at a certain point at sunrise and then ends at sunset along the eclipse belt. About half a circle around the earth from the starting point to the end point. The eclipse must happen in the new moon, which is the first day of the lunar calendar. At this time, the moon is located between the earth and the sun, but because the orbit of the sun (ecliptic) and the orbit of the moon (ecliptic) are at an angle of 5 9', there is not always an eclipse on the first day, but when the eclipse occurs, both the sun and the moon must occur near the "yellow-white intersection" (rising intersection or falling intersection).

2. Sharo cycle

The same solar eclipse (total solar eclipse, annular solar eclipse and partial solar eclipse) will occur once every 1 1 day or 6585.32 days (Charro cycle), but the observable areas are different, and the types of solar eclipses are not necessarily the same only when the eclipse time is the same. Because the length of the Charlotte cycle is 6585.32 days, it is not an integer, so if there is another solar eclipse in the same place on the earth (not necessarily the same type of solar eclipse), you have to wait for three Charlotte cycles. The next solar eclipse will occur in one-third of the Charlotte cycle after each solar eclipse, and reappear in the same area after three Charlotte cycles of about 54 years and 33 days. At present, there are 12 different big Sharo cycles, one of which occurred in 1937, 1955, 19 1 and in 2009 (China Yangtze River valley, Wuhan and Hangzhou), which lasted for about 7.5 minutes.

The eclipse belt is the shadow of the moon.

The moving speed of the eclipse belt (the shadow of the moon) in the equatorial region is about 65,438+0,65,438+000 miles per hour, and it reaches 5,000 miles per hour at the poles. The widest total solar eclipse zone is 167 miles. In the area where the total solar eclipse passes, the range of partial solar eclipse can be seen as high as 3000 miles. The total solar eclipse belt generally passes through the ocean or barren places.

4. The principle of solar eclipse

An eclipse is when the moon moves between the sun and the earth. If the three are in a straight line, the moon will block the light from the sun to the earth, and the shadow behind the moon will just fall on the earth. At this time, the eclipse happened. People in the shadow of the moon on the earth began to see the sun gradually weakening, and the sun was covered by a circular shadow. When the sky is dark and completely covered, the brightest stars and planets can be seen in the sky. After a few minutes, the sun gradually emerged from the shadow edge of the moon and began to shine and make the last contact.

[Edit this paragraph] The significance and value of total solar eclipse

The main reason why total solar eclipse is paid attention to is its great astronomical observation value. Many important astronomical and physical discoveries in the history of science were made by the opportunity of total solar eclipse, and only through this opportunity can they be made. The most famous example is a total solar eclipse in 19 19, which confirmed the correctness of Einstein's general theory of relativity. Einstein published the general theory of relativity in 19 15, which was extremely difficult to understand and incredible at that time. This theory predicts that light will turn in a huge gravitational field. The strongest gravitational field that humans can contact is the sun, but the sun itself emits strong light, and it is impossible to see whether the faint starlight in the distance turns when passing near the sun. However, if a total solar eclipse occurs and the sunlight is blocked, it can be measured whether the light has turned. The opportunity appears in 19 19, but the total lunar eclipse is in the South Atlantic, which is far away and difficult. British astronomer Eddington set out with an enthusiastic and curious observation team. The observation results are very consistent with Einstein's pre-calculation results, and the theory of relativity has been recognized by the world since then.

In China, the first two total solar eclipses can only be seen in remote areas. One time was in 1980, which was only visible in Ruili, Yunnan, on the border between China and Myanmar, and the other time was after the Spring Festival in 1997, which was visible in Mohe, the northernmost part of China, on the border between China and Russia. At that time, the author was ordered by the newspaper to interview and gave up his childhood dream. The scale of that observation was beyond imagination. Astronomers and amateurs from all over the world are crowded in a small town in northern Xinjiang, which is usually inaccessible and more lively than Chinese New Year. Because the number of people greatly exceeds the reception capacity of the town, people can only camp on trains and cars. At that time, it was still winter there. During the day, the temperature is about MINUS 25 degrees Celsius, and at night it can reach MINUS 40 degrees Celsius, dripping into ice, and people can't even find water to wash their faces and gargle. Nevertheless, no observer regrets and no one is not excited. They all regard seeing the total solar eclipse with their own eyes as a rare and precious memory in life. Astronomical phenomena such as total solar eclipse have nothing to do with people's daily life. Eat and drink Lazar. But it represents an ultimate humanistic concern, an extreme love for nature, and an eternal curiosity and awe of the iron law of nature that governs everything. A country, a nation, can't live without these concerns, these passions, these curiosities, and these awe.

The upcoming total solar eclipse on July 22, 2009 is becoming the focus of social and media attention. When you pay attention to the best observation points, observation equipment and other news, do you also know some basic knowledge of total solar eclipse? Please note-

"God-given opportunity, don't miss the' secret'." On July 22nd, domestic astronomers lamented China's excellent "secret" of observing the 500-year total solar eclipse. This is the most spectacular total solar eclipse in this century. It is rare that the solar eclipse has a wide area, a long time and a large population. However, when you pay attention to the best observation points, observation equipment and other news, do you also know the most basic knowledge of total solar eclipse?

Why do total solar eclipses always appear in different places?

The observable range of this total solar eclipse covers many large and medium-sized cities and densely populated areas in the middle and lower reaches of the Yangtze River and South Asian countries. However, the last total solar eclipse occurred on August 1 day, 2008, and only a few remote areas in northwest China were suitable for observation. As we all know, the eclipse is because the moon blocks the sunlight. When a solar eclipse occurs, the area covered by the moon forms a shadow "cone" between the moon and the earth, and the total solar eclipse can only be seen when the surface of the earth rubs it. Due to the limitation of the orbit of the sun and the moon, the surface can be cut to the largest cross section of the "cone" with a diameter of less than 270 kilometers. As the earth rotates, it sweeps through a narrow area where you can see the total solar eclipse. Every time a total solar eclipse occurs, the time, the relative position and angle of the earth and the moon are different, so the "cone" of the moon shadow will sweep across different places on the earth. Although the total solar eclipse does not have the periodicity of comets and meteor showers once in a thousand years, for a certain area, the "once-in-a-century" that media merchants vigorously exaggerate is not an exaggeration.

Why is the scope and duration of each observation different?

The total solar eclipse on July 22 will last for 6 minutes and 39 seconds (the longest in China is 5 minutes and 55 seconds), and it can be seen in China with a land bandwidth of about 250 kilometers, which will be the longest duration and the largest population in China in this century. The orbit of the moon around the earth and the orbit of the earth around the sun are elliptical, and the distance between the earth and the moon and the sun is always changing. The diameter of the sun is about 400 times that of the moon, so only when the orbits of the sun and the moon "meet" and the distance between the sun and the earth is at least 400 times that of the sun and the earth can the moon completely block the direct sunlight of the sun and form a total solar eclipse. When the total solar eclipse came, the sun was near the apogee, the moon just passed the perigee, and the shadow of the moon swept a large area of the earth. More than 80% of the earth's surface is ocean and sparsely populated areas, so it is rare for the moon shadow to sweep through densely populated areas. The angular velocity of the moon's revolution around the earth is much higher than that of the earth's revolution around the sun, so the shadow of the moon moves very fast on the surface of the earth, about 1800 km/h in the equatorial region and as high as 8000 km/h near the poles, so the total solar eclipse at the equator can last for about 7 minutes and 40 seconds at the highest, but only a few minutes at the middle and high latitudes, and there is no total solar eclipse at the poles.

Why does total solar eclipse seem less common than total lunar eclipse?

Shen Baofeng, an outstanding historical and cultural scholar and young songwriter in Handan, has studied the phenomenon of total solar eclipse in ancient tombs of Han Dynasty for a long time, and came to the conclusion that all ethnic groups have different interpretations of total solar eclipse, such as dogs eating the sun and wolves eating it day by day, and each has its own solutions. In ancient China, people dealt with it by beating gongs and drums. Because the total solar eclipse usually lasts for a short time (seven and a half minutes at most), the sun may reappear immediately after people knock on the door, avoiding people's panic. China recorded the solar eclipse long ago, and many stones were dug up in the tombs of the Han Dynasty. These stones depict many figures of the sun, the moon and the stars, and one of them depicts "the combination of the sun and the moon", that is, the sun and the moon are stacked together, which is the record of the solar eclipse at that time. China people's scientific explanation of solar eclipse is that Yin invades Yang. China knew long ago that the moon regarded as "Yin" covered the sun regarded as "Yang", which led to the solar eclipse. In ancient times, there was a saying that "the full moon will eclipse", which meant that all eclipses occurred at the full moon. When the solar eclipse occurred, the ancient court of China would also take action; People in China believe that the sky represents nature, and the sun occupies the highest position in nature. The emperor is called the son of heaven, which means that he was sent by heaven to manage the people. Since Heaven represents the emperor's father, Heaven will warn his agent on the ground, the emperor, through the phenomenon on the surface of the sun, and make it clear that he is doing something wrong and should be careful. Therefore, through various signs, solar eclipse is a situation that is often used. According to the records in the ancient book Bizhen Dian, during the solar eclipse in Han Dynasty, the emperor did not go to the main hall to do the early dynasty, but went to the small hall next to the partial hall to do the early dynasty, so everything was simple.

In terms of the number of global occurrences, there are actually more solar eclipses than lunar eclipses in a year. From the earth, the trajectories of the sun and the moon intersect once every six months, and the cycle of solar eclipse (eclipse season) may be longer than that of lunar eclipse (eclipse season). There may not be an eclipse in a year, but there must be two or five eclipses. On average, there will be a total solar eclipse every 1.5 years in the world. However, once an eclipse occurs, half the earth can see it in the dark. The total lunar eclipse lasts for tens of minutes or even hours, and the observable range and duration are much longer than the total solar eclipse, so the probability of being seen in the same place is higher.

Why is the interval between every two total solar eclipses in the same area different?

As the best observation area in the middle and lower reaches of the Yangtze River in China, the last total solar eclipse was in 1575 434 years ago, and the next one will be in 2309 300 years later. Ancient astronomical observers concluded that the phase transition period of 223 months at the same place was basically the same as the time when the sun passed through the intersection of the sun and the moon, forming a period of about 18 years. Since then, people have proposed other more perfect periods. Because of observation, the change period of the sun and the moon can only be calculated by integers, but the lengths of the two are not exactly equal. Coupled with the influence of the earth's rotation, two solar eclipses separated by one cycle often do not occur in the same place, and it is not necessarily a total solar eclipse or a partial solar eclipse, and the time required for a total solar eclipse to return to the same place is even more uncertain. However, astronomers have adopted strict

Through calculation, the time of the first underground total solar eclipse can still be accurately predicted.

During the total solar eclipse, what impact may it have on the ground?

Different from clouds blocking the sun on rainy days, during the total solar eclipse, the ionosphere at the height of the atmosphere will change with the moon blocking the solar radiation. This will temporarily interfere with the medium-wave and short-wave communication in which the signal needs to be reflected by the ionosphere, while FM broadcasting, mobile phones and wireless Internet access using ultrashort waves will not be affected. However, for the whole earth's magnetic field, this effect is still very small. In addition, during the total solar eclipse on August 1 day, 2008, the temperature at the observation point in Yiwu, Xinjiang dropped by about 8 degrees Celsius, and many observers also felt that the surrounding area was getting cold. The solar eclipse mainly occurred in the middle and lower reaches of the Yangtze River. In summer, the temperature difference between day and night in urban areas generally does not exceed 5 degrees Celsius, and it also occurs in the morning of the recovery period, so the temperature drop caused by the solar eclipse will not be great.

When a total solar eclipse occurs, why can you look directly at the sun with the naked eye within a few minutes?

Except for the total solar eclipse, the sun is completely covered by the moon for a few minutes, so you can look at the total solar eclipse directly with the naked eye, and you must never look at the sun directly with the naked eye at the rest of the time, let alone use a telescope that lacks a special filter for the sun. Within a few minutes of the total solar eclipse, the brightest ball of the sun was completely covered. At this time, you can directly observe the sun with the naked eye or telescope and enjoy the corona and stars exposed in the sky. The camera or video camera should also remove the filter at this time, otherwise it will only take a dark picture. However, the total lunar eclipse lasts for a short time and will soon return to a partial eclipse. Even if only a small part of the photosphere is exposed, its brightness is enough to harm human eyes and photographic equipment. Therefore, it is still necessary to prepare eclipse observation glasses, lens filters and so on. Advance, and grasp the time of the total lunar eclipse.

Why not watch the total solar eclipse as a "lifelong regret"?

Many people who have personally watched the total solar eclipse believe that it is irreplaceable for any photo or video to witness the sky turning black and the red sun turning into a spectacle full of stars. Rare sights such as Bellevue, corona and prominence fascinate astronomy lovers, and ordinary people who are not interested in astronomy at ordinary times will add a little curiosity. Living in the middle and lower reaches of the Yangtze River, being able to watch the total solar eclipse at home is of course an adventure in life, but for many people in northern China and Lingnan who have no chance to see the total solar eclipse this time, if they are really interested in it and have the conditions to travel abroad, they can join the ranks of "global trackers" of the total solar eclipse, and the average waiting time of one and a half years is not too long. Future prediction of total solar eclipse

1: China will enjoy three eclipses in the next four years; China will have its first total solar eclipse in this century. In the next four years, the Chinese public can also enjoy three rare total solar eclipses, including one total solar eclipse and two annular solar eclipses. Astronomical experts say that it is rare to see so many eclipses in five years. Zhao Zhi Heng, director of the Tianjin Astronomical Society, said that since the 1980s, there have been two total solar eclipses in China, one in southwest cities such as Kunming and Guiyang, with the time of1980; One occurred in Mohe area of 1997. "The total solar eclipse this year and next, whether it is the scope of the total solar eclipse belt or the time when the total solar eclipse occurs, is conducive to public observation in China. As long as the weather is good, the public can feast their eyes. " Zhao Zhi Heng said. In addition to the total solar eclipse on August 1 2008, a more spectacular total solar eclipse will occur in China on July 22, 2009, which will sweep across the Yangtze River valley in central China. By then, more than 40 cities in China, including Lhasa, Chengdu and Shanghai, can watch the total solar eclipse. Compared with the total solar eclipse in August 1 day, this total solar eclipse has a wider range and a longer duration, which will reach 5 to 6 minutes. This situation can be described as once in a hundred years. In addition to these two total solar eclipses, there was another annular eclipse on June 5 at 20 10+ 10, and the public in Yunnan, Sichuan, Hubei, Anhui and other places could have a glimpse of the annular eclipse. On May 2, 2065438, the solar eclipse was staged again, and the public in Guangxi, Guangdong, Fujian, Hong Kong and Macao could enjoy it. Astronomical experts say it is rare to see so many eclipses in five years.

2. The forecast time of solar eclipse in major cities of China in 2008 and the situation of seeing the eclipse: On August 1 day, a total solar eclipse occurred in Altay, Xinjiang, China, from Hami, Jiuquan and Xi 'an to Zhengzhou, starting at about 8: 20 Beijing time1day and lasting about two minutes. This is the first total solar eclipse in China in 2 1 century.

[Edit this paragraph] Eclipse process

The process of total solar eclipse can include the following five periods: initial loss, eclipse, eclipse, luminescence and last contact.

First contact (of an eclipse)

Because the moon orbits the earth from west to east, the solar eclipse always starts from the western edge of the sun's circular surface. When the eastern edge of the moon just touches the round surface of the sun (that is, when the eastern edge of the moon is tangent to the western edge of the sun), it is called the initial loss. The first loss is the moment when the eclipse begins.

The second contact of total solar eclipse

Judging from the initial loss, it is a partial eclipse stage. The moon continues to move eastward, the part of the sun's circular surface covered by the moon gradually increases, and the intensity and heat of sunlight are obviously reduced. When the eastern edge of the moon surface is inscribed with the eastern edge of the sun surface, it is called eclipse. At this time, the entire circular surface of the sun is covered, so the solar eclipse is the moment when the total solar eclipse begins.

Mid eclipse

After the eclipse, sun gear will continue to move eastward. When the center of sun gear is closest to the center of the sun's surface, it will be full.

third contact

For partial solar eclipse, the solar eclipse is the moment when the sun is covered by the moon the most. The moment when the moon continues to move eastward and the western edge of the moon meets the western edge of the sun is called luminescence, which is the moment when the total solar eclipse ends. Before the birth of light, diamond rings and Bailey beads would appear again on the western edge of the sun, but they would soon disappear. Then, a dazzling light shines on the west of the sun. Chromosphere, prominence and corona, which can be seen during the total solar eclipse, disappeared in the sun, the stars disappeared and the sun lit up again.

Final contact

After the light is generated, the surface of the moon continues to be far away from the surface of the sun, and the part of the sun that is blocked gradually decreases. The moment when the western edge of the moon surface is tangent to the eastern edge of the sun surface is called the last contact. At this time, the sun showed a disc shape again, and the whole process of total solar eclipse came to an end.

[Edit this paragraph] Bailey beads, diamond rings

When the sun is about to be completely blocked by the moon, a diamond-like arc light will suddenly appear on the eastern edge of the sun, just like the striking shining light on the diamond ring. This is the diamond ring, and at the same time, a string of luminous highlights will be formed in an instant, hanging high in the dark sky like a string of dazzling pearls. This phenomenon is called pearl food, which was first described by British astronomer Bailey, so it is also called Bailey beads. This is because there are many rugged peaks on the surface of the moon. When the sun shines on the edge of the moon, the Bailey bead phenomenon is formed. Bailey beads appear for a short time, usually only one or two seconds, and then the sun is completely blocked, resulting in a total solar eclipse.

magnitude of eclipse

Used to indicate the degree of solar eclipse. For solar eclipse, solar eclipse does not refer to the area covered by the circular surface of the sun, but refers to the ratio of the covered part of the diameter of the sun to the diameter of the sun. Take the diameter of the sun as 1, and if the solar eclipse is 0.5, it means that the diameter of the sun is covered by half; If the solar eclipse is 1, it means that the entire round surface of the sun is covered, and that is a total solar eclipse. Obviously, the larger the part, the greater the degree to which the sun is covered. The food fraction of partial solar eclipse is less than 1.0, and that of total solar eclipse is less than 1.0.

Food belt

Because the shadow cone of the moon is thin and long, when it falls on the earth's surface, it occupies a very small area, no more than one tenth of the total area of the earth, and the maximum diameter is only more than 260 kilometers. When the moon revolves around the earth, the shadow cone sweeps a relatively long area from west to east on the ground, and a solar eclipse can be seen in the area swept by the shadow of the moon. So this belt is called "Eclipse Belt". If there is a total solar eclipse in the belt, it is called a total solar eclipse belt; If there is an annular eclipse in the belt, it is called an annular eclipse belt. It can be seen that the range of partial solar eclipse is very wide, not like a strip, but a large area.

The total solar eclipse belt is a narrow path with a width of only two or three hundred kilometers and a length of several thousand to 10000 kilometers (sometimes the width of the total solar eclipse belt is only a few kilometers). Only in the area swept by the total solar eclipse belt can we see the occurrence of total solar eclipse or annular solar eclipse. On both sides of the total solar eclipse belt is a relatively wide penumbra swept area, where you can see the partial solar eclipse. The closer to the total eclipse zone, the greater the degree of partial eclipse; The farther away from the belt, the smaller the degree of partial eclipse; You can't see the eclipse beyond the penumbra.

Because the moon moves from west to east, its shadow also moves in the same direction, so the time to watch the solar eclipse varies from place to place. When the western area on the ground is already in the shadow area, people in this area have already seen the solar eclipse, but people in the eastern area can't see the solar eclipse at the same time, and they can't see the solar eclipse until the moon shadow moves eastward. Therefore, westerners always see solar eclipses before orientals.

Eclipses occur every year, but because the total eclipse belt is a narrow strip, it is estimated that every 200 ~ 300 years, a certain area or city will have the opportunity to be swept by the total eclipse belt. Therefore, for people living in a city, they may have never seen a total solar eclipse in their lives.

The solar eclipse in China in this century

August 0, 20081total solar eclipse

The total solar eclipse can be seen in parts of Xinjiang Uygur Autonomous Region, Gansu Province, Ningxia Hui Autonomous Region, Shaanxi Province, Shanxi Province and Henan Province in China. In China, Jinchang, Gansu Province is a good observation site.

Total solar eclipse on July 22, 2009

The best observation area of this total solar eclipse in China is the Yangtze River Basin, which lasts for a long time. In addition, partial solar eclipses of different degrees can be seen in most parts of China.

20 10 1 15 solar eclipse

China Central City: northern Yunnan, southern Sichuan, northern Guizhou, Chongqing, northern Hubei, southeastern Shaanxi, most of Henan, most of Shandong, northern Anhui and northern Jiangsu.

2065438+annular solar eclipse on May 20, 2002

China Central City: the southeast of Guangxi Zhuang Autonomous Region, most of Guangdong Province, most of Hong Kong, Macau, Fujian Province and the northeast of Taiwan Province Province.

Annular eclipse on July 2, 20201day

South-central Xizang Autonomous Region, south-central Sichuan, north-central Guizhou, central Hunan, southwestern Jiangxi, southern Fujian and south-central Taiwan Province Province.

Annular eclipse on June 0 1 day, 2030

China Central City: Northeast Inner Mongolia Autonomous Region, north-central Heilongjiang Province.

Total solar eclipse on March 20, 2034

China Total Food Zone: North of Xizang Autonomous Region, Southwest of Qinghai Province.

Total solar eclipse on September 2, 2035

China total food area: south-central Xinjiang Autonomous Region, north-central Gansu Province, west-central Inner Mongolia Autonomous Region, northern Shanxi Province, central Hebei Province, most of Beijing, northern Tianjin and southern Liaoning Province.

204 1 1 October 25th annular solar eclipse

China Central City: North-central Inner Mongolia Autonomous Region, North Liaoning Province and Southwest Jilin Province.

Annular eclipse on July 0 1 day, 2057

China Central City: the eastern edge of Xinjiang Autonomous Region and the northern edge of Gansu Province.

Total solar eclipse on April 30, 1960

China Total Food Zone: the central part of Xinjiang Autonomous Region, at the junction of Qinghai Province and Gansu Province.

1total solar eclipse on August 24, 963

China's total grain area: east of central Xinjiang Autonomous Region, central Inner Mongolia Autonomous Region, most of Jilin Province and southeast Heilongjiang Province.

Annular eclipse on February 6, 2064 at 5438+07.

China Central City: Central Xizang Autonomous Region, Southeast Qinghai Province, Northwest Sichuan Province, Central Gansu Province, Most of Ningxia Autonomous Region, Southwest Inner Mongolia Autonomous Region, North Hebei Province, Northwest Jilin Province and Southwest Heilongjiang Province.

Total solar eclipse in April 2070 1 1 day

China Total Food Zone: Xisha Islands, the southernmost coastal area of Taiwan Province Province Island.

65438+20741October 27th annular solar eclipse

China Central City: Southeast of Guangxi Zhuang Autonomous Region, Central of Guangdong Province, Southeast of Jiangxi Province and Central of Fujian Province.

65438+2085122 October annular eclipse

China Central City: southern Yunnan Province, northern Guangxi Autonomous Region, southern Hunan Province, central Jiangxi Province and northern Fujian Province.

1April 2, 9881total solar eclipse

China Total Food Zone: the border areas in the middle of Xinjiang Autonomous Region, northern Qinghai Province and southwestern Gansu Province.

165438+ 19951October 27th.

China Central City: the northeast of Hebei Province, the northeast of Beijing, Chifeng area of Inner Mongolia and the south of Liaoning Province.

[Edit this paragraph] Century solar eclipse

July 22, 2009: solar eclipse of the century. Because the black shadow of the moon first landed in the Arabian Sea, and then passed through central and northeastern India, southeastern Nepal, most parts of Bhutan, northern Bangladesh, the easternmost and southern India, and central Tibet, it was the longest total solar eclipse in 2 1 century. Soon, the shadow of the moon will pass through central China, and then move to the East China Sea of China and parts of Ryukyu Islands. About 200 meters east-southeast of Iwo Jima is the best place to observe this solar eclipse. For some people, this may be the most perfect solar eclipse in 2 1 century. It is the longest solar eclipse between 199 1 and 2 132.

Matters needing attention in observing total solar eclipse

Observing the sun is very dangerous because it emits strong visible light, infrared light and ultraviolet light. Ultraviolet rays not only burn the skin, but also cause rapid damage to the retina of the eyes. As long as human eyes look directly at the sun for a few seconds, it may cause permanent damage or even blindness. If the sun is observed through a telescope without proper dimming equipment, the consequences will be even more unimaginable. Partial solar eclipse and annular solar eclipse can't be watched without special safety measures. In the partial eclipse stage of the total solar eclipse, even if the surface of the sun is covered by the moon for 99%, the photosphere formed by the new moon will still cause harm to the eyes. Don't try to observe the sun with the naked eye at any stage of partial or annular solar eclipse.

Here are some scientific observation methods for you:

Ink observation method (but this method is not recommended because of its low dimming rate and easy eye injury)

You can take a basin of water, add ink, and see the sun through the reflection of water.

Pinhole projection method

Make use of two boards, dig a small hole in one board, and let the sunlight pass through this small hole and project onto the other board.

telescope projection method

Don't shake your hands, or the shadow of the sun will run back and forth. Never look directly at the sun with a telescope. If you look at the sun directly with a telescope, you must use a filter.