Why is the moon in lunar calendar 15 round?

Reason: As the saying goes, "the moon on the 15th has sixteen laps". Experts say that people say this because the moon revolves around the earth in an elliptical orbit. It takes an average of 29 days 12 hours and 44 minutes from one full moon to the next. When you look at it, the moon, the earth and the sun are closest to a straight line, so the moon is the roundest and brightest. However, due to the different speed of the moon, the time to reach Wangwang is also different, mostly in the early morning of the lunar calendar 16 or even 17.

In August this year, astronomical "hope" will appear at 10 0 1 on August 15 (September 18), so you can enjoy the beautiful full moon on the night of Mid-Autumn Festival this year.

Why "the moon on the fifteenth is sixteen circles"? Astronomers say that this is because the full moon can only be seen when the longitude difference between the moon and the sun is 180 degrees and the positions of the moon and the sun are completely opposite to the earth (just like two people face to face). However, the moon's orbit around the earth is elliptical, near and far; 360,000 kilometers recently and 400,000 kilometers farthest. Because of "gravity", it walks fast in the near future and slowly in the far future.

If the first half of the month is fast, it will arrive at the position of the full moon on time, on the fifteenth lap; If it is slow, it will be "late", and 16 or 17 will reach the full moon position. It is not surprising that the tenth five-year plan has not been put in place. The moon in August this year is a little slow, so the 1 1 point on the 16th (tomorrow) of the lunar calendar will be the most round time.

When the moon moves in the opposite direction to the sun, we can see the full moon.

This is called "look".

When the moon moves between the earth and the sun, the half moon illuminated by the sun is just behind the earth, so we can't see it.

Seeing the moon is called "new moon".

From "Wang" to "Wang" or from "New Moon" to "New Moon", it takes an average of 29 days 12 hours and 44 minutes.

This is called the new moon.

The new moon must be on the first day of every month in the lunar calendar.

On average, there are 14 days and 18 hours and 22 minutes before the new moon.

So the full moon often happens not on the night of the fifteenth, but on the night of the sixteenth.

As the saying goes, "the moon on the fifteenth day is sixteen circles", which is the reason.

Because the revolution speed of the moon around the earth is uneven, sometimes fast and sometimes slow, therefore,

The length of the first month of the lunar calendar can be 6 hours different from its average, so the full moon can also be delayed to 17 nights.

Of course, if the new moon happens in the early morning of the first day, it will happen on the fifteenth night.

Therefore, it is also possible to hope that the year just happened in the Mid-Autumn Festival.

Because the full moon can only be seen when the longitude difference between the moon and the sun is 180 degrees and the positions of the moon and the sun are completely opposite to the earth (just like two people face to face). However, the moon's orbit around the earth is elliptical, near and far; 360,000 kilometers recently and 400,000 kilometers farthest. Because of gravity, the near segment is fast and the far segment is slow. If the first half of the month is fast, it will arrive at the full moon position on time, in the fifteenth round. If you are slow, you will be "late" and arrive at the full moon position on the 16th or 17th.

It seems verbose. Please be patient.

Hope to adopt