Why is the moon on the fifteenth day of this year seventeen round?

Why is the moon on the fifteenth day of this year seventeen round?

CCTV news:It is said that “the moon on the fifteenth day is sixteen round”, however, astronomers’ calculations show that the full moon moment of this year’s Mid-Autumn Festival is neither on August 15th nor August 16th in the lunar calendar, but on August 17th, which is September 27th. What’s going on?

It is understood that the brilliance of the moon comes from sunlight. As the moon orbits the earth, the relative positions of the sun, the earth, and the moon are constantly changing. When the moon moves between the sun and the earth, we cannot see the moon, which is called “Suo”. This day is the first day of the lunar calendar. When the moon turns behind the earth and the bright side is facing the earth, it is called “Wang”. At this time, what we see is the full moon. From synodic to lunar month, it takes an average of 14.77 days; a complete synodic month lasts on average 29.53 days.

The moon’s orbit is not perfectly circular and the full moon times are sequential