Think about it, the moon rotates in the same amount of time as it rotates, so how many degrees does the moon rotate and how many degrees does it rotate around the earth. You can only see 59% of the moon when you're standing on Earth, you'll never see the rest unless you use a spacecraft.
The ancient name "Shuoze," or the cycle of the moon's phases, means that the moon's phases change.
In the vast starry sky, the most striking celestial body is the moon, its ever-changing appearance, which carries so many beautiful and touching myths and legends from ancient times to the present day, for the human world to add a lot of poetry and picturesque! In the Guanghan Palace, there are Chang'e fairies dancing. Not only that, the moon's cyclical cycle is still one of the basis for people to develop the calendar since ancient times.
The Moon revolves around the Earth and also rotates in the same direction with the same period (this is called "synchronized rotation"), so the Moon is always facing the Earth with the same face, and people have never seen the back of the Moon's head in the long years before satellites hit the sky. Why does the moon vary? As you know, the moon itself does not emit light, but only reflects a portion of the sunlight that shines on it, so that, for observers on Earth, the moon takes on different shapes on different days as the relative positions of the sun, moon, and Earth change, which is the cyclical change of the moon's phases. Further, although there is always half a sphere of the moon that is bright when it is illuminated by the sun, because the moon is constantly revolving around the earth, changing its position from time to time, the half of its sphere directly facing the earth and the half illuminated by the sun sometimes coincide completely, sometimes do not coincide at all, sometimes a small portion of it coincides, and most of it does not; and sometimes a large part of it does and a small portion of it does not. In this way the moon exhibits variations of yin and yang. When the Moon is between the Sun and the Earth, its dark hemisphere is facing us, and we can't see any image of the Moon at all, which is called the "solstice", and the solstice refers to the moment when the Moon's ecliptic meridian is the same as the Sun's. On a solstice, the Moon and the Sun's ecliptic meridian are the same. On the first day of the month, the moon and the sun rise from the east at the same time, even if the earth reflects the sunlight to the moon, and then the moon reflected back by the part of the light, but also completely submerged in the strong sunlight. And when the Earth is between the Moon and the Sun, although the three planets are also in a line, but this time, the Moon is lit by the Sun hemisphere toward the Earth, the soft moonlight on the earth all night, this is the full moon, also known as the "hope". This is when the moon's ecliptic and the sun's ecliptic differ by 180 degrees. Because the distance between the Moon and the Earth is too short relative to the distance between the Sun and Earth, on the celestial sphere, the Moon's eastward speed is much larger than the Sun, the Moon advances more than 13 degrees eastward from west to west every day, while the Sun advances only one degree. After the solstice, therefore, the moon quickly runs to the east of the sun, and a day or two later, as soon as the sun goes down, a crescent moon can be seen in the western sky, with its two pointed corners pointing to the east. Thereafter, the moon rises later and later, and the moon gradually becomes fuller. About seven days after the first day of the lunar month, the moon's yellow meridian is just over 90 degrees above the sun, and we see the moon as a semicircle with its arc facing west, which is the epicyclic moon. Later, the moon continues eastward and becomes fuller and rises later until the first day of the month. From Solstice to Hope, the moon moves further and further away from the sun. After Wang, the Moon gradually moves closer to the Sun, and the lunar surface gradually thins out.? When the moon's ecliptic longitude exceeds the sun's ecliptic longitude by 270 degrees, it becomes semicircular again, but with the arc of the circle facing east, which is the hypocyclic moon. At this time, when the sun rises in the east, the moon is hanging high in the sky due south, naturally, our naked eye cannot see the moon at this time. After the lower quarter of the moon, the moon does not come out from the east until the latter part of the night, and its half-circle is gradually eroded down to a narrow sickle shape, with its sharp corners pointing to the west. From wang to solstice, the moon and the sun closer and closer, so that once again the same as the sun's yellow meridian, disappeared in the morning sun. The cycle of moon phase changes, that is, the time from solstice to wang or from wang to solstice, is called the lunation. Observations show that the length of the lunar month is not fixed, sometimes as long as 29 days and 19 hours more, sometimes only 29 days, 6 hours and 4 minutes more, ? Its average length is 29 days, 12 hours, 44 minutes and 3 seconds. The interval between the moon and a star in the middle of the sky twice at the same time is called the sidereal month, the sidereal month is the true cycle of the moon's motion around the Earth. The lunar month is longer than the sidereal month for the same reason that the solar day is longer than the sidereal day. The sidereal month has little to do with daily life, but the lunar month is because the moon is the cycle of changes in the moon's roundness, and the earth's tides and ebb and flow of the tide is related to sailing, fishing has a close relationship with the people's activities at night have a greater impact on the moon phase of the religion also occupies an important position, so people naturally take the lunar month as a longer than the day of the timekeeping unit. To show you a picture of the back of the moon.