Traditional Culture Encyclopedia - Weather forecast - Formation of solar eclipse
Formation of solar eclipse
scientific explanation
A solar eclipse is a typical example of light traveling in a straight line in a celestial body. When the moon moves between the sun and the earth, it is not always like this. When a lunar eclipse occurs, two conditions need to be met. First of all, the solar eclipse always happens on the first day of the lunar calendar. Not all eclipses will happen on the first day of the lunar calendar, because the orbit of the moon (ecliptic) and the orbit of the sun (ecliptic) are not on the same plane. There is an included angle of 59 between the ecliptic plane and the ecliptic plane. On the first day, if both the sun and the moon move near the intersection of the ecliptic and the ecliptic, and the sun and the intersection form a certain angle (eclipse limit), an eclipse will occur, which is the second condition to be met.
Because the orbits of the moon and the earth are not perfect circles, and the distance between the sun and the moon is near or far, the shadow formed by the sun being blocked by the moon can be divided into umbra, pseudo-umbra (formed when the moon is far away from the earth) and penumbra on the earth. The observer can see the total solar eclipse in the umbra; Annular eclipse can be seen in the range of pseudoumbra; Only a partial solar eclipse can be seen in the penumbra.
When the total solar eclipse occurs, it can be divided into five eclipse images according to the positional relationship between the round surface of the moon and the round surface of the sun: 1. Initial loss. The moon moves faster than the apparent speed of the sun. The moon caught up with the sun during the eclipse. When the eastern edge of the moon just "touches" the western edge of the sun, it is called the first loss, which is the first "circumscribed" and the beginning of the solar eclipse. 2. Eat well. About an hour after the initial loss, the moment when the eastern edge of the moon "cuts in" with the eastern edge of the sun is called an eclipse, which is the beginning of the total solar eclipse, when the moon covers the whole sun; 3. Eat a lot. It is the deepest eclipse moment of the sun, and the center of the moon moves to the center closest to the sun; 4.light. The moment when the western edge of the moon and the western edge of the sun "cut in" is called light, which is the end of the total solar eclipse; It usually takes only two or three minutes from eating to lighting, and the longest is no more than seven and a half minutes; 5. Last contact. About an hour after the birth of light, when the western edge of the moon "touches" the eastern edge of the sun, it is called the last contact. Since then, the moon has completely "left" the sun, and the eclipse is over.
There are many mountains on the surface of the moon, and the edge of the moon is irregular. At the moment of the lunar eclipse or the arrival of light, when the valley on the edge of the moon fails to completely cover the sun, the uncovered part forms a luminous area, like a crystal diamond; The reddish aperture around constitutes the "ring" of the diamond ring, which looks like a diamond ring inlaid with bright gems. Sometimes a lot of particularly bright lights or spots are formed, like a string of pearls embedded around the sun. This phenomenon is called Bell Pearl (Belle is a French astronomer).
Whether it is a partial solar eclipse, a total solar eclipse or an annular solar eclipse, the time is very short. The area where the solar eclipse can be seen on the earth is also limited, because the moon is relatively small and its umbra is relatively small and short, so the umbra will not sweep the earth for a long time. Because the average length of the umbra of the moon (373,293 kilometers) is shorter than the average distance between the moon and the earth (384,400 kilometers), there are more annular eclipses on the whole earth than total solar eclipses.
frequency of occurrence
The following are the global solar eclipses in the 20th century (190 1- 1999):
Partial eclipse 78
Annular eclipse 73
Total solar eclipse 7 1
Mixed food 6
A total of 228 people
The process of lunar eclipse
After the total lunar eclipse, the penumbra begins to eclipse: the moon just touches the penumbra, which is invisible to the naked eye at this time.
The process of a formal eclipse can be divided into five stages: initial loss, eclipse, eclipse, luminescence and last contact.
Initial loss:
Marks the beginning of the solar eclipse. The moon slowly entered the shadow from the eastern edge, and the umbra of the moon and the earth was delineated for the first time.
Eat both:
The western edge of the moon is inscribed with the western edge of the earth's umbra, and the moon just completely enters the earth's umbra.
Eat a lot:
The center of the moon is closest to the umbra center of the earth.
Original light:
When the total lunar eclipse phase is over, the eastern edge of the moon is inscribed with the eastern edge of the Earth's umbra.
Last contact:
The western edge of the moon is tangent to the eastern edge of the umbra of the earth, and then the whole eclipse process ends.
The degree of eclipse is called "eclipse", which is equal to the ratio of the farthest distance from the edge of the moon wheel to the umbra of the earth and the meridian of the moon when the eclipse is serious.
End of the penumbra eclipse: The moon leaves the penumbra, and the whole eclipse process officially ends.
Knowledge of watching solar eclipse
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During this period, the sun will not emit any special rays. Observations of solar eclipses are often misinterpreted. The sun will not predict the occurrence of solar eclipse on the earth, nor will it emit other rays, so it is harmless to stay outdoors during the solar eclipse. But should we stare at or glance at the partial eclipse? Although the sunlight during the eclipse is much weaker than usual, if you look straight, it will still hurt your eyes and cornea. People stare or squint at the sun out of curiosity. Of course, the partial solar eclipse is still very dazzling. If you watch the sun for a long time, your cornea will be damaged unconsciously. During the eclipse, the eyes were damaged not because of the abnormality of the sun, but because people were curious and didn't pay attention to protective measures. No matter whether the eclipse occurs or not, don't look directly at the sun with your eyes; Don't use so-called "sunglasses"; Don't use "sunglasses", not even a few folded ones; Don't look at the image of the sun in the mirror or on the water;
Looking at the sun with a welding mirror14; Watch it with a specially coated Myra mirror, which can be obtained from the famous planetarium or science museum; Build an aperture projector.
The story of solar eclipse
For ancient people, the solar eclipse was very terrible. If you can understand the influence of the sun on grain planting and daily life, you will be concerned about why the sun suddenly disappeared in the sky. In ancient China, people thought that the solar eclipse was caused by a dragon devouring the sun. Other civilizations also think this is an ominous sign, and there are many "solutions": playing drums, shooting arrows at the sky, taking things or offering sacrifices to people. It is said that there was a fatal solar eclipse report error. This means that two astronomers in China in the 2nd century BC did not report the solar eclipse for some reason. At that time, Emperor China thought he was the son of heaven and attached great importance to astronomical phenomena. He thought it was a hint from heaven, so he invited a group of astronomers to observe the astronomical phenomena regularly. At that time, comets and meteors could not be predicted, but eclipses could be predicted. The two astronomers didn't tell the emperor about the solar eclipse, and the emperor was furious and beheaded them. Astronomers then were much more dangerous than they are now.
appendix
Knowledge about the sun
solar prominence
Prominence is a kind of solar activity phenomenon that protrudes beyond the edge of the sun's surface. When prominence appears, colored balls in the atmosphere resemble burning grasslands, and rose-red tongue-shaped gas rises like fire, with different shapes, some like clouds, some like arch bridges, some like fountains, some like clumps of grass, and some are as beautiful as festive fireworks. On the whole, they are shaped like earrings attached to the edge of the sun, hence the name "prominence". Prominences rise about tens of thousands of kilometers. Large prominences can be hundreds of thousands of kilometers higher than the surface of the sun, with a general length of about 200,000 kilometers, and individual prominences can reach 1.5 million kilometers. Prominences are much darker than the photosphere, so they can't be observed with the naked eye at ordinary times, and can only be seen directly during a total solar eclipse. Prominence is a very strange phenomenon of solar activity. Its temperature ranges from 5,000 to 8,000. Most prominences rise to a certain height and then slowly land on the surface of the sun. However, some prominences float in the lower layer of the corona, and the temperature is as high as 2 million K, which is as strange as a piece of unmelted ice in a hot steelmaking furnace. In addition, the density of prominence is 654,330 higher than that of corona.
solar corona
The outermost atmosphere of the sun is called the corona. The corona extends several times to dozens of times the diameter of the sun. In the most active year of solar activity, the corona is close to a circle; In quiet years, it is oval.
B] There are large irregular dark areas in the corona, which are called coronal holes. Coronal hole is an area with low gas density in the corona. There are three kinds of coronal holes: polar coronal holes, isolated coronal holes and extended coronal holes. Solar energy loses material in the form of solar wind-material particle flow. Coronal hole is an important source of high-speed solar wind. Coronal mass ejection (CME) is a very macroscopic and huge material and magnetic field structure that occurs in the corona. It is a sudden explosion phenomenon of large-scale dense plasma. Nothing can affect the earth more than it. When there is a strong explosion and coronal mass ejection on the sun, the powerful plasma flow carried by the solar wind may reach the polar regions of the earth. At this time, the aurora appears at the poles of the earth. The forms of aurora are ever-changing. Aurora has also been found on some planets with magnetic fields in the solar system. Flares occurring in the corona are called X-ray flares, and their wavelength is only 1 ~ 8 Angstroms or less. It directly causes the disturbance of the earth's ionosphere, thus affecting the earth's short-wave communication.
Rilang
An ejection phenomenon of solar photospheric matter. It usually occurs over sunspots and has strong reproducibility. When a broken wave falls behind along the rising path, it will trigger a new broken wave to take off, and so on, but the scale and height are getting smaller and smaller every time until it disappears. Surfing at the edge of the sun looks like a bright hill with a sharp peak at the top. The height of the rise is different. Small surfing is only a few hundred kilometers, big surfing can reach 5000 kilometers, and the maximum surfing can reach 1 ~ 20000 kilometers. The maximum speed of the projectile can reach 100 ~ 200 kilometers per second, which is more than 100 times faster than the fastest reconnaissance plane. When they reach the highest point, they begin to descend under the influence of the sun's gravity until they return to the surface of the sun. From the high-resolution observation data, it is found that surfing is composed of a very small bundle of fibers, and each bundle of fibers is very small apart, which shines and moves together as a whole.
Solar activity forecast
The change of the state of space environment between the sun and the earth is becoming more and more important to the modern cutting-edge technology on which modern life and production depend. As mentioned earlier, X-ray flares directly cause ionospheric disturbances on the earth, thus affecting short-wave communication on the earth. Solar proton events will endanger the sensors and control equipment of astronauts and spacecraft, and also pose a radiation threat to passengers and crew flying at high latitudes. According to statistics, strong solar activity is related to earthquakes, volcanic eruptions, droughts and floods, heart and nervous system diseases and traffic accidents. Therefore, solar activity and solar-terrestrial physical prediction are very important. Solar activity forecasting is divided into long-term, medium-term and short-term forecasting and early warning. As a systematic scientific research object, the space environment of the sun and the earth began in 1957 when humans entered space. The 1950s and 1970s were the exploration stages, and people gradually realized the importance of space environment. On the basis of a lot of exploration, a static model describing the environment is established and some important spatial activities are predicted. After 1980s, driven by demand, the research on the space environment of the sun and the earth developed rapidly. Since 1979, the international conference on solar-terrestrial prediction has been held as scheduled every four years, and its scale has been expanding. In order to unite and coordinate the work of major countries, a joint forecasting center was established. Headquartered in the United States, there are 10 regional alarm centers distributed all over the world. Our Beijing alarm center is one of them. After entering the 1990s, scientists vividly called it "space weather".
Solar activity cycle
The average period is 22 years, and it includes two sunspot cycles of 1 1 year. In each cycle, the polarity of sunspots is opposite, and the changes of other solar phenomena have two highs and two lows like sunspots. These solar phenomena include prominence, flare and frequency fluctuation of magnetic effect, and magnetic effect includes aurora and enhancement of radio interference to the earth. The basic sunspot cycle (sometimes called solar activity cycle) of1year was announced by Schwabe in 1843. Some people try to link the solar activity cycle with the changes of other phenomena, such as small changes in the diameter of the sun. Even the change of tree rings is related to the solar cycle.
The earliest record of solar eclipse
On May 26th, 65438 BC+0265438 BC+07 BC, people living in Anyang, Henan Province were carrying out various normal activities, but amazing things happened. People looked up at the sky, and the radiant sun suddenly appeared a gap, and the light was dim. However, after missing a large part, it began to recover. This is the earliest solar eclipse record in human history. It was carved on a piece of Oracle Bone Inscriptions.
The observation of solar eclipse in ancient China kept the continuity of records. For example, Spring and Autumn Annals records that there were 37 eclipses in 244 years from 770 BC to 476 BC. The record of solar eclipse from the 3rd century A.D. continued to modern times, lasting 16700 years.
The longest solar eclipse.
The longest duration of an eclipse (the moon is between the sun and the earth) is 7 minutes, 365,438+0 seconds. 1955 occurred in western Philadelphia, and the solar eclipse lasting 7 minutes and 8 seconds was the longest in recent years. It is predicted that there will be a solar eclipse lasting 7 minutes and 29 seconds in the middle of the Atlantic Ocean in 2 186. 1995, a mother and son were photographed during an eclipse in Bangkok, Thailand, which was a total solar eclipse in some parts of the country. The longest duration of an eclipse (the shadow of the moon moving to the earth) is 1 hour and 47 minutes. On July 16, 2000, people saw this scene on the west coast of North America.
Because the orbits of the moon and the earth are not perfect circles, and the distance between the sun and the moon is near or far, the shadow formed by the sun being blocked by the moon can be divided into umbra, pseudo-umbra (formed when the moon is far away from the earth) and penumbra on the earth. The observer can see the total solar eclipse in the umbra; Annular eclipse can be seen in the range of pseudoumbra; Only a partial solar eclipse can be seen in the penumbra.
Ten-year eclipse schedule
The best observation point of year, month and day type
February 7, 2008 near Antarctica and the Pacific Ocean
Canadian, Arctic Ocean, Soviet Union and China.
2009 1 26 ring the atlantic, Indian Ocean, Indonesia
July 22nd, 2009, all over India, China and the Pacific Ocean.
20 10 1 15 Africa, Indian Ocean, Myanmar, China.
The entire Pacific Ocean and southern South America
20 12 5 2 1 around China, Japan, the Pacific and the United States.
All of Australia and the Pacific.
20 13 5 10 Australia, Irian Island and Pacific Rim
All over the Atlantic and Africa.
Around Antarctica 20 14 4 29
20 15 3 20 Atlantic Ocean, Spitsbergen Islands, Arctic Ocean
20 16 3 9 all over Indonesia and the Pacific ocean
20 16 9 1 ring the atlantic, Africa, Indian Ocean
20 17 2 26 Pacific Rim, South South America, Atlantic Ocean and Southern Africa
20 17 8 22 Pacific, America and Atlantic
20 19 7 3 All Pacific and South America
20 19 12 26 Rim Arabia, India, Indonesia and the Pacific Ocean
2020 6 2 1 Africa, Arabian Peninsula, Pakistan, China, Pacific Ocean.
2020 12 15 All Pacific Ocean, Southern South America and Atlantic Ocean
202 1 6 10 Northeast North America, Arctic Ocean and around the Soviet Union
202 1 12 4 Atlantic, Antarctica and Pacific Ocean
On April 20, 2023, the Indian Ocean, Irian Island and the Pacific Ocean were circled.
2023 10 15 Pacific Rim, Southern North America, Northern South America and Atlantic Ocean
2024 4 9 Pacific Ocean, Southern North America, Atlantic Ocean
2024 10 3 Pacific Rim, South America, Atlantic Ocean
2026 2 17 Antarctic and Indian Ocean periphery
August 202613 The whole Arctic Ocean, Greenland, Atlantic Ocean and the westernmost part of Europe.
February 6, 2027, the edge of the Pacific Ocean, the southernmost part of South America, the Atlantic Ocean.
2027 8 2 Atlantic Ocean, Far North Africa, Far West South Asia, Indian Ocean
2028 1 26 Pacific Rim, North America, South America, Atlantic Ocean and Western Europe
2028 7 22 All Indian Ocean, Australia and Pacific Ocean
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