How is the eclipse formed?

Eclipse is a special astronomical phenomenon, which means that when the moon moves to the shadow of the earth, the area between the moon and the earth will be blocked by the earth because of the sunlight, and the moon will be missing. At this time, the sun, the earth and the moon are exactly (or almost) on the same straight line. Eclipses can be divided into three types: partial eclipse, total eclipse and penumbral eclipse. A solar eclipse can only occur around the fifteenth day of the lunar calendar.

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.

1, the penumbral eclipse begins: the moon just touches the penumbra, and at this time, the surface brightness of the moon drops slightly, but it is difficult for the naked eye to detect.

2, the first loss (only partial eclipse and total eclipse): marks the beginning of the 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 full moon surface is closest to the center of the Earth's umbra. At this time, the surface of the moon is red copper or dark red. (Cause: When sunlight passes through the earth's atmosphere, it refracts, which makes the light deflect inward, but the degree of deflection (dispersion) of each light is different. The red light has the largest deflection and is closest to the shadow of the earth, which is reflected 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.

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 and 7, it can be detected with the naked eye.