Isn't the fifteenth lunar month a full moon? Why is there an eclipse?

In fact, there is a certain relationship between the moon's profit and loss and the eclipse, because the eclipse is that the earth is on the same line of the sun and the moon, and it is often a full moon or near a full moon (around the fifteenth day of the lunar calendar). Similarly, solar eclipses often occur on the first day of the lunar calendar.

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.

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.