Total Eclipse of the Sun
The sun is 400 times wider than the moon, but it is also 400 times farther from the earth. Because of symmetry, the shadow of the moon, that is, the shadow that falls on the surface of the earth, is just wide enough to cover the whole sun. The sun ball is completely covered by the moon, and the original bright sun disk is covered by the shadow of the moon. However, only when the total solar eclipse occurs can the fuzzy corona be observed by the naked eye. Total solar eclipse will only happen when the moon is at perigee, when the length of the umbra cone of the moon is longer than the distance between the moon and the earth, so that the umbra cone can sweep across the earth's surface. Because the actual volume of the sun is much larger than that of the moon, the total solar eclipse can usually only be seen in a small area on the earth, because the umbra of the moon is only a small point of the sun. Outside the total eclipse area, the solar eclipse you see is a partial eclipse.
partial solar eclipse
China's history books say that "the sun has food, and life is endless". The reason for the partial solar eclipse is that the observer falls in the penumbra of the moon. The observer will see that part of the sun is covered by the shadow of the moon, but the other part continues to shine. The sun and the moon only partially overlap, and the food intake is measured according to the apparent distance between their centers (the maximum diameter of the moon covering the sun). Usually partial solar eclipse is accompanied by other solar eclipses, such as total solar eclipse or annular solar eclipse or total solar eclipse. But some eclipses in the polar regions will be simple partial eclipses (no other eclipses), because the distance between the moon and the ecliptic plane is a little far, and only the penumbra touches the earth's surface.
annular solar eclipse
When the moon is at apogee, the umbra cone of the moon cannot reach the earth; What reaches the earth is the pseudo-umbra cone extended from the umbra cone. At this time, the apparent diameter of the moon is slightly smaller than that of the sun. Therefore, the photosphere on the edge of the sun is still visible at this time, forming a bright ring around the shadow of the moon. Outside the eclipse belt, the solar eclipse seen is a partial eclipse.
Total Eclipse of the Sun
Only when the earth's surface is very close to the top of the lunar umbra, or the distance between the moon and the earth's surface is very close to the length of the lunar umbra, will a total lunar eclipse occur. Because the earth is a sphere, when the umbra cone touches the earth, it is a total solar eclipse (usually in the middle of the eclipse zone). Because the umbra cone can't touch the earth at both ends of the food belt, only the pseudoumbra can reach below the earth, and it sees an annular eclipse. Therefore, when the total solar eclipse occurs, with the relative movement of the earth and the moon, there will be annular eclipses → total solar eclipse → annular eclipse one after another. Of course, for a specific place, it is impossible to see a total solar eclipse and an annular solar eclipse at the same time in an eclipse. The occurrence of total solar eclipse is rare.
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 earth (ecliptic) are not on the same plane. There is an included angle of 59 between the ecliptic plane and the ecliptic plane. Secondly, both the sun and the moon move near the intersection of the ecliptic and the ecliptic, and the sun forms a certain angle with the intersection (eclipse limit).
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.
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. The whole looks like a diamond ring inlaid with bright gems, which is called "diamond ring". Sometimes many particularly bright lights or dots are formed, like a string of pearls embedded around the sun. This phenomenon is called "Bailey Pearl" (Bailey 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.
Eclipse
When a total solar eclipse occurs, it can be divided into five kinds of solar eclipse images according to the positional relationship between the moon and 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 and the eastern edge of the sun "cut in" is called a lunar eclipse, which is the beginning of a total solar eclipse (or annular eclipse). For a total solar eclipse, the moon covers the whole sun at this time, and for an annular eclipse, the sun begins to form a ring. During the eclipse, the positional relationship between the shadow of the moon and the first inscribed circle of the sun also refers to the moment when this positional relationship occurs.
The eclipse occurred after the initial loss. From the initial loss, the moon continued to move eastward, the part of the sun's circular surface covered by the moon gradually increased, and the intensity and heat of sunlight decreased obviously. When the eastern edge of the moon surface is inscribed with the eastern edge of the sun surface, it is called eclipse. The direction of the sky is opposite to that of the map.
3. Eat a lot. It is the deepest eclipse moment of the sun, and the center of the moon moves to the nearest distance from the center of the sun; In the process of partial solar eclipse, when the sun is covered by the moon the most, the positional relationship between them; In the process of total solar eclipse and annular solar eclipse, when the sun is completely covered by the moon and the distance between the two centers is the closest, the positional relationship between them. It also refers to the moment when the above positional relationship occurs.
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 time is no more than seven and a half minutes.
For an eclipse, after the eclipse, the appearance of the moon continues to move eastward for the sun.
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.
Total solar eclipse and annular solar eclipse have the above five processes, while partial solar eclipse has only three processes: initial loss, extreme eclipse and last contact, without food and light.
Overview of lunar eclipse
Eclipses can be divided into three types: partial eclipse, total eclipse and penumbral eclipse. When only a part of the moon enters the umbra of the earth, there will be a partial lunar eclipse; When the diameter of the umbra 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. If the moon is always only partially obscured by the umbra of the earth, that is, only a part of the umbra of the earth, a partial lunar eclipse will occur. There will be no annular eclipse on the moon. Because the moon is smaller than the earth and is within the umbra of the earth, there will be no eclipse. The number of solar eclipses occurs twice a year, up to three times, and sometimes none at all. Because under normal circumstances, the moon either passes above the Earth's umbra or leaves from below, rarely or partially passes through the Earth's umbra, so an eclipse will not occur under normal circumstances. According to the statistics of observation data, the percentage of lunar eclipse, partial eclipse and total eclipse in the penumbra in each century is about 36.60%, 34.46% and 28.94%.
Eclipse
1. The penumbral eclipse begins: The moon just touches the penumbral region, and at this time, the surface luminosity of the moon is slightly reduced, but it is difficult for the naked eye to detect.
2. Initial loss (only partial solar eclipse and total solar eclipse): marks the beginning of the lunar 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.
3. Eclipse (total lunar eclipse only): The moon enters the umbra of the earth and intersects the earth for the first time. The moon has just entered the umbra of the earth.
4. What to eat: The moment when the center of the round moon surface is closest to the center of the Earth's umbra, when the moon surface is red copper or dark red. (Cause: When sunlight passes through the earth's atmosphere, it refracts, causing the light to deflect inward, but the degree of deflection (dispersion) of each light is different, and the red light has the largest degree of deflection, which is closest to the earth's shadow and reflects on the moon; In addition, due to the different contents and positions of dust and clouds in the atmosphere, the degree of light deflection will be different, so the moon will appear dark red, copper or orange during the total lunar eclipse. Similarly, due to the refraction of the atmosphere, the sunrise and sunset are not white, but orange or red according to the height because of the different degrees of atmospheric refraction. )
5. Luminescence (total lunar eclipse only): The moon moves in the umbra of the earth and cuts into the umbra of the earth for the second time. 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.
6. Last contact (partial and total solar eclipses only): The moon gradually leaves the Earth's umbra and is tangent to the Earth's umbra for the second time. 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.
7. End of the penumbra eclipse: The moon leaves the penumbra, and the whole eclipse process officially ends. The partial eclipse of the moon has no process of eclipse and light generation, and the eclipse only represents the moment closest to the shadow of the earth. (Twelve constellations/Astronomy/)
The degree of lunar eclipse is expressed by food score. The ratio of the apparent diameter of the moon to the apparent diameter of the moon during an eclipse. When the food is very heavy, just like the moon and the umbra, the eclipse is equal to 1. When the monthly eclipse is severe, if the moon goes deep into the umbra, the monthly eclipse is indicated by a number greater than 1. The food intake of total lunar eclipse is greater than or equal to 1. The score of food with partial eclipse is less than 1. A penumbral eclipse is expressed by the ratio of the part of the moon's diameter entering the penumbra to the apparent diameter of the moon. When the eclipse of the penumbra is greater than 0.7, it can be detected with the naked eye.