When did the solar eclipse happen and why?

Judging from the time of solar eclipse and lunar eclipse, the time of solar eclipse is often on the first day of each month in our lunar calendar, while the eclipse is on the fifteenth day of each month.

On the first day of every month, the position of the moon is just between the sun and the earth. It rises and sets at the same time as the sun, which is called the new moon in the lunar calendar, that is, the day when the moon cannot be seen. However, due to the revolution of the earth and the moon, sometimes the moon will become a line with the sun and the earth, and the area covered by the moon will form a solar eclipse. The area where you can't see the sun at all is a total solar eclipse, and the area where you can partially see the sun is a partial solar eclipse. Also, at a certain time, the moon can be seen blocking the middle part of the sun in a certain area, which is an annular eclipse. This is related to the perigee and apogee of the moon revolution and the position of the earth orbit.

The15th of every month is the day of full moon, which is mentioned in the lunar calendar. The sun goes down, the moon rises, and the sun, the earth and the moon are also on the same line. The earth is sandwiched between the sun and the moon. If the earth just blocks the light from the sun to the moon, the earth's shadow will be cast on the moon, and then there will be an eclipse. Eclipses will of course be divided into total solar eclipse, partial solar eclipse and annular solar eclipse.