The process of solar eclipse and lunar eclipse

Eclipse Eclipse is that the moon goes around the earth and moves between the sun and the earth. This is the first day of the lunar calendar. If the sun, the moon and the earth are in a straight line, the moon blocks the sunlight that hits the earth, and the shadow behind the moon just falls on the earth, then a solar eclipse occurs. 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. Because the moon is smaller than the earth, only people in the shadow of the moon can see the solar eclipse. Total lunar eclipse occurs when the moon blocks all the sun, partial solar eclipse occurs when the moon blocks part of the sun, and annular solar eclipse occurs when the moon blocks the central part of the sun. The total solar eclipse lasts no more than 7 minutes and 58 seconds. China has the oldest solar eclipse record in the world, and there have been exact solar eclipse records for over 0/000 years BC. Whether it is a partial solar eclipse, a total solar eclipse or an annular solar eclipse, the time is very short. Watch the total solar eclipse in the same place for no more than seven minutes and forty-five seconds. 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. Prominence prominence is a phenomenon of solar activity 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. 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. 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. Solar wave surfing is also called "solar wave". 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. It is more and more important for modern life and production to predict the change of space environment between the sun and the earth by solar activity. 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". The time interval between several important solar activities. 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 the slight change of the diameter of the sun, the change of tree rings, and even the fluctuation of the stock market. Eclipse is a special astronomical phenomenon, which means that when the moon moves to the shadow part of the earth, the area between the moon and the earth will be blocked by the earth because of sunlight, and now the moon is gone. That is to say, at this time, the sun, the earth and the moon are just (or almost) in a straight line, so the light from the sun to the moon will be blocked by the earth. As far as the earth is concerned, when an eclipse occurs, the directions of the sun and the moon will be different by 180 degrees, so the eclipse must occur at' Wang' (that is, around the lunar calendar 15). It should be noted that the orbits of the sun and the moon in the sky (called the ecliptic and the ecliptic) are not on the same plane, but have an intersection angle of about 5 degrees, so only when the sun and the moon are located near the intersection of the ecliptic and the ecliptic can they be connected in a straight line to produce an eclipse. Classification of solar eclipses The diameter of the earth is about four times that of the moon. In lunar orbit, the umbra diameter of the earth is still 2.5 times that of the moon. So when the centers of the earth and the moon are roughly on the same straight line, the moon will completely enter the umbra of the earth, resulting in a total lunar eclipse. But if only a part of the moon is always covered by the umbra of the earth, that is, only a part of the moon enters the umbra of the earth, a partial lunar eclipse will occur.

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