What does it mean that dogs eat the moon?

Eating the moon by tengu refers to the phenomenon of lunar eclipse.

Eclipse is a special astronomical phenomenon, which means that when the moon moves to the shadow part of the earth, the area between the moon and the earth will see that the moon is gone, because the sunlight is blocked by the earth. 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.

There will be a shadow on the earth far away from the sun, which is called the earth shadow. The earth's shadow is divided into umbra and penumbra. The umbra refers to a place that is not exposed to direct sunlight, while the penumbra is only exposed to some direct sunlight. In the process of orbiting the earth, the moon sometimes enters the shadow of the earth, resulting in an eclipse. When the whole moon enters the umbra, a total lunar eclipse will occur; But if only a part of it enters the umbra, only a partial lunar eclipse will occur. Total lunar eclipse and partial lunar eclipse are umbra eclipses.

Extended data

There is a legend in ancient China that "dogs eat the moon", that is, the shadow of the earth will slowly cover the moon, because sunlight will penetrate the atmosphere. When the moon is completely covered, a dark red moon will appear in the sky. In A.D.110, there were records at home and abroad that "the moon suddenly disappeared in the sky".

According to NASA's records, from 1 100 to 1 120, seven eclipses were observed in Europe, among which the "eclipse" in May of10/0 impressed many witnesses-the moon was completely. The magical phenomenon of this eclipse made many astronomers talk about it until hundreds of years later. For nearly a thousand years, astronomers have been trying to solve the mystery of the disappearance of the moon. Recently, researchers have studied and analyzed ice cores (samples collected from the depths of ice sheets or glaciers), and finally concluded that the drastic changes in the earth's atmosphere thousands of years ago may be the "culprit" of this event.