The specific reasons are as follows:
An eclipse is when the sun, the moon and the earth are on the same line. The moon blocks the sun, so the sun can't be seen in some parts of the earth, even during the day. When the sun is completely covered, it is called total solar eclipse, and the covered part is called partial solar eclipse.
And the eclipse, it is the performance ball on the same straight line that blocks the sun and makes the moon dark in the clear night sky. Similarly, lunar eclipses are also divided into total solar eclipse and partial solar eclipse.
In ancient China, because people didn't understand the reason of the eclipse, they thought it would be a catastrophe. Therefore, in ancient times, people called the lunar eclipse "Tengu eats the moon". Now we know that solar eclipse and lunar eclipse are both natural phenomena of light's linear propagation law.
Question 2: How are solar and lunar eclipses formed?
When the moon comes to the sunny side of the earth and its shadow sweeps across the area, people see that the sun is covered by the moon wheel, which is called an eclipse; When the moon goes around the earth with its back to the sun, it happens to be hidden in the umbra of the earth. At this time, from the perspective of the earth, the full moon loses its luster in the sky, which is an eclipse. It is conceivable that when there is an eclipse, you will see an eclipse in the sky of the moon; When there is a solar eclipse on the earth, a small darkness appears on the bright "place" in the moon night sky, which can be called "Lingdi", as shown in the following figure:
Eclipses are divided into three categories: total solar eclipse, partial solar eclipse and annular solar eclipse. Among them, total lunar eclipse and annular eclipse are also called annular eclipse. At the same time, annular and partial solar eclipses occurred in different parts of the earth; Before and after the central food in the same area, there must be a partial eclipse stage. There is an annular eclipse at the beginning and end of the eclipse, and a total solar eclipse occurs in the middle stage, as shown below. This eclipse is called total solar eclipse.
Eclipses are divided into total solar eclipse and partial solar eclipse, and there is no annular solar eclipse. Before and after the total lunar eclipse, there must be a partial lunar eclipse. Whether it is a total solar eclipse or a partial solar eclipse, similar eclipses can be seen all over the world (night hemisphere). When the moon enters the penumbra of the earth, there will be no "eclipse", because part of the sun's brilliance can be obtained in the penumbra, and it still illuminates the whole surface of the moon, but the brightness becomes slightly darker, and the moon wheel is still indispensable. This phenomenon is called a penumbral eclipse. As for why there is no eclipse, the reason is that the cross section of the penumbra is much larger than that of the moon wheel outside the orbital distance of the moon.
Total solar eclipse can be divided into three stages: partial solar eclipse-total solar eclipse-partial solar eclipse, and there are four stages of lunar eclipse: initial loss, second eclipse, light generation and last contact. In the process of solar (lunar) eclipse, the moment when the center of the moon wheel is closest to the center of sun gear or umbra section is called an eclipse. When the food is heavy, the degree to which the sun or the moon is "eaten" is called food division. The same solar eclipse, different parts of the food and time; But in the same eclipse, as long as you can see the whole process, the time to eat and see the food is the same.
The general conditions for the occurrence of solar (lunar) eclipses are ① the conditions for looking ahead: the eclipse must occur in the new moon and the eclipse must occur in the line of sight. (2) Intersection conditions: the solar eclipse occurs in the new moon, and the eclipse is in sight; However, not every new moon will have an eclipse, and not every moon will have an eclipse. The condition of solar eclipse is that the sun and the moon meet at or near the intersection of yellow and white; The condition of an eclipse is that the sun and the moon collide (seemingly) at or near the intersection of yellow and white.
Globally, there are more eclipses than eclipses. But for a place, the number of eclipses is far more than the number of eclipses. Because during the eclipse, the eclipse area is wide (it can be seen everywhere in the night hemisphere), while during the eclipse, only a very narrow area can be seen on the earth. According to statistics, for a specific place, a total lunar eclipse will occur every three or four years on average, but only once every few hundred years (there will be a total lunar eclipse in China on July 22nd, 2009). 1the annular solar eclipse on September 23rd, 987 also reappeared on October 3rd, 2005/kloc-0.