The ancients often described the full moon as reunion, and the waning moon as separation.
The full moon in ancient times represented family reunion, happiness, and harmony; a good life; the waning moon: in ancient times, the waning moon represented separation and the pain of lovesickness; the famous poem in "Shui Diao Ge Tou": "People have joys and sorrows, and the moon waxes and wanes." Therefore, most of the time in ancient times, the full moon represented unity and the waning moon represented separation.
On the night of the Mid-Autumn Festival, the moon is bright and clear. The ancients regarded the full moon as a symbol of reunion. Therefore, August 15th is also called the "Reunion Festival". Throughout the ages, people have often used the words "full moon and waning moon" to describe "joys and sorrows", and wanderers living in foreign lands use the moon to express their deep feelings. Poet Li Bai of the Tang Dynasty wrote "Looking up at the bright moon, bowing head thinking about my hometown", Du Fu's "The dew is white tonight, the moon is bright in my hometown", Wang Anshi of the Song Dynasty wrote "The spring breeze is green on the south bank of the river, when will the bright moon shine back on me" and other poems, They are all eternal songs.
Song Dynasty scholar Shen Kuo studied astrophysics intensively. In his representative work "Mengxi Bi Tan", he vividly explained the principle of the full moon phase: the moon itself does not emit light, but the sun shines on it to make it bright. As time goes by, the position between the sun and the moon changes, and the illuminated areas are also different, so the world will have a visual waxing and waning change. Now to be precise, the phases of the moon are the result of regular changes in the relative positions of the sun, earth and moon.
Introduction to the Moon
The Moon (English name: Moon, Latin: Luna) is a spherical celestial body that rotates around the Earth and is also a natural satellite of the Earth. The moon is the fifth largest satellite in the solar system. Its average radius is about 1737.10 kilometers, which is equivalent to 0.273 times the radius of the Earth. Its mass is close to 7.342×10 kg, which is equivalent to 0.0123 times the radius of the Earth. The moon's surface is covered with impact craters that may have been formed by impacts of small celestial bodies. The average distance between the moon and the earth is about 384,400 kilometers, which is about 30 times the diameter of the earth.
The moon has a fluid outer core and a solid inner core similar to the Earth. The moon is a natural satellite of the earth. It may have been formed about 4.5 billion years ago. Shortly after the formation of the earth, there are several hypotheses about its origin. The one supported by more factual evidence is that it was formed from a celestial body the size of the earth and Mars. ——The "big collision origin theory" formed by the debris produced by a huge impact between "Theia" and gathered on the outer periphery of the earth.