There is an appointment in the starry sky.

Xinhua News Agency, Nanjing, September 8th. "One year's monthly color is the lowest, and people's hearts are rewarded together." September 10 will usher in the annual Mid -Autumn Festival. Astronomical popular science experts told reporters that Mid -Autumn Festival this year is the "fifteenth moon of the fifteenth moon", and the largest time for the full moon of the Mid -Autumn Festival is 17:59 on September 10. In the evening, a round of full moon rises is the time when the public is good.

The origin of the Mid -Autumn Festival and the moon are inseparable. Zhang Yan, director of the Science Popularization Department of the Zijin Mountain Observatory of the Chinese Academy of Sciences, introduced that there are many definitions based on the "month" determined by the moon's revolution. The average length is about 29.53 days. The July, August and September of the lunar calendar are autumn, and August 15th of the lunar calendar is called "Mid -Autumn Festival" in the middle of the autumn.

In the process of turning around the earth for a week, from the perspective of the earth, the different appearances of the moon are "moon phases". That is, the moon is sometimes like a narrow crescent, sometimes like a round. Zhang Yan said that the starting point of the monthly phase change cycle is a specific moment, called "Shuo", which is called "Shuo Ri" on the same day. At this time, the moon is in the middle of the earth and the sun, which cannot be seen for ground observer.

Beijing astronomical enthusiast Wu Luping, October 1, 2020 (August 15th of the lunar calendar) in Dingdu Pavilion, Beijing. (I have a picture)

The most round moment of the moon is called "Wang", and the day is "Wangri". "Wang" corresponds to the about the midpoint of each lunar month. At this time, the moon is located near the extension of the Japanese connection, and the entire hemisphere of the earth is illuminated by the sun. Therefore Full moon.

Jiangxi Province astronomical enthusiast Shen Lin September 21, 2021 (August 15th of the lunar calendar) in Tengwangge, Nanchang, Nanchang. (I have a picture)

"Looking at the day of the lunar calendar depends on the specific moment of Shuo and the time interval between Shuo Wang." Zhang Yan said that taking the Mid -Autumn Festival this year as an example, the Shuo in August of the lunar calendar occurred at 16:17 on August 27th. The interval between Shuangwang was 14 days, 1 hour and 42 minutes, and the hope occurred at 17:59 on September 10. It happened that day was August 15th of the lunar calendar, so this year's Mid -Autumn Festival "Fifteen Moon Fifteen Circles".

The full moon does not necessarily appear in the fifteenth lunar calendar, but may appear in the fourteenth to seventeen of the lunar calendar. In the past 10 years, the earliest Mid -Autumn Festival in the Gregorian calendar was September 8, 2014. At that time, the most loose time at the time of the Mid -Autumn Festival appeared at 9:38 in the lunar calendar; the latest Mid -Autumn Festival was October 4, 2017 On the day, the corresponding moon is at 2:44 August 17th. Zhang Yan introduced that starting in 2021, the Mid -Autumn Festival for three consecutive years will be "fifteen moon fifteen circles." (Reporter Wang Yan, Qiu Bingqing, Zhou Runjian)

[Editor in charge: Wu Yongling]

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