Why is the moon round on August 15

The reason why there is a folk saying that "the moon is 15 and 16 rounds" is because the moon revolves around the earth in an elliptical orbit, and it takes an average of 29 days, 12 hours and 44 minutes from one full moon to the next full moon. When "looking", the moon, the earth, and the sun are closest to a straight line, so the moon is also the roundest and brightest. However, due to the speed of the moon, the speed of the moon varies from one time to another, and most of them are in the early morning of the 16th, 15th, and even 17th lunar calendar.

The lunar calendar has 12 months of the year, and on the fifteenth day of each month, the moon is rounded once. But why is it so bright from the moon to the Mid-Autumn Festival? From a meteorological point of view, this is because at this time, the cold and dry air currents blowing from the north force the warm, moist air that has been swirling over most parts of the country in summer to retreat southward, and the clouds and fog in the sky are reduced.

At the same time, the inclination of the sun gradually increases, the sunlight and heat obtained by the ground gradually decreases, the temperature is getting lower day by day, the autumn wind reduces the water vapor, and the air is transparent, so that the night sky is like a wash, and the moon is exceptionally bright.

Of course, this is also relative. From an astronomical point of view, the moon is not necessarily only visible in the Mid-Autumn Festival. Because the moon is only bright when it reflects the sun's light, from the perspective of the earth, the strength of the moonlight is not only related to the size of the moon's reflective surface seen by the earth, but also related to the distance of the moon from the earth and the distance of the moon from the sun.

When the moon reflects the sun's rays on the largest lunar surface and is nearly perfectly round, then the moonlight should be the brightest, generally on the 15th or 16th or even 17th of the lunar month; At the same time, the Moon's orbit around the Earth is elliptical, and the perigee is not necessarily fifteen; In addition, the Earth's orbit around the Sun is also elliptical, and perihelion is generally on the lunar calendar.

Ten. January, December, not August.

It can be seen that the saying that the moon to the Mid-Autumn equinox is also relative, and it contains a certain kind of sustenance and feelings of people.

Because on the fifteenth day of the lunar calendar, the moon moves on the celestial sphere to directly opposite the sun.

It's time for the lunar calendar. Ten.

At 5 or 16 o'clock, the moon runs directly opposite the sun on the celestial sphere, and the sun and the moon are 180 degrees apart, that is, the earth is located between the sun and the moon. The full moon rises in the east at dusk and sinks west at dawn.

On the first day of the lunar calendar, the moon will move between the earth and the sun, and when its ecliptic longitude is the same as the sun's ecliptic longitude, the moon's illuminated hemisphere is facing away from the earth, so people on the earth cannot see the shining side of the moon, which is called Shuo, which is commonly known as the new moon.

And around the fifteenth day of the lunar calendar, the moon has gone to the other side, the earth is between it and the sun, when it is 180 degrees different from the sun's ecliptic longitude, the bright side of the moon will all face the earth, so at this time we see the round moon, which is called Wang, which is commonly known as the full moon.

The moon is round on the fifteenth day of each month (lunar calendar), that is for sure. But none of them are as round as August 15.

Because the angle of the moon facing the earth on the fifteenth day of each month is not the same, the roundness of the moon on the fifteenth day of each month is also different. On August 15, the Moon has a better angle towards the Earth, so it looks rounder.

Of course, the speed at which the moon revolves around the earth is getting slower and slower, so that in a few hundred thousand years, the moon will become more and more round, less and less than fifteen circles per month.

The moon is at its roundest at 5 o'clock on August 15. The brightest night of the moonlight of the year, when thousands of miles of people enjoy it together", September 10 will usher in the annual Mid-Autumn Festival. Astronomical science experts told reporters that this year's Mid-Autumn Festival is "the fifteenth moon and fifteenth round", and the fullest moment of the Mid-Autumn Festival is 17:59 on September 10.

In the evening, a full moon rises, which is the best time for the public to enjoy the moon.

Meaning:

The origin of the Mid-Autumn Festival is inseparable from the moon. There are various definitions of "month" based on the moon's revolution around the earth, one of which is called "synodic month" according to the waxing and waning cycle, which is the basis for determining the month in the lunar calendar, and its average length is about days. Lunar calendar.

July, August and September are autumn, and the 15th day of the eighth month of the lunar calendar is in the middle of autumn, which is called the "Mid-Autumn Festival".

The above content reference: Encyclopedia - Mid-Autumn Festival.

The Mid-Autumn Festival in 2022 is the fifteenth round of the moon, and the roundest moment of the moon occurs at 17:59 on September 10.

According to the Chinese calendar, the eighth month of the lunar calendar is in the middle of autumn, which is the second month of autumn, which is called "Mid-autumn", and August 15 is in the middle of "Mid-autumn", so it is called "Mid-Autumn Festival".

The Mid-Autumn Festival is also known as the Moon Festival, the Autumn Festival, the August Festival, the August Festival, the Moon Chasing Festival, the Moon Playing Festival, the Moon Worship Festival, the Daughter's Day or the Reunion Festival. The Mid-Autumn Festival is a traditional festival in China. According to historical records, the term "Mid-Autumn Festival" first appeared in the book "Zhou Li".

By the time of the Wei and Jin dynasties, there was a record of "Yu Shangshu Town Cattle Confusion, Mid-Autumn Festival Eve and Left and Right Micro Service Panjiang". It was not until the early years of the Tang Dynasty that the Mid-Autumn Festival became a fixed festival. "Tang Shu Taizong Ji" records that "August 15th Mid-Autumn Festival".

The popularity of the Mid-Autumn Festival began in the Song Dynasty, and by the time of the Ming and Qing dynasties, it had become one of the main festivals of China's wheel and erection on the same level as New Year's Day. This is also the second major traditional festival in China after the Spring Festival.