Reasons why Binh Ngo Lunar New Year 2026 has no 30th day
For 8 consecutive years, from 2025 to 2032, December will only have 29 days, and New Year's Day will fall on the 29th of Lunar New Year instead of the 30th as usual.
To explain this phenomenon, we need to pay attention to the type of calendar that countries are using. Currently, countries and peoples around the world use three main calendar types: solar calendar, lunar calendar and lunar calendar.
In which, the calendar takes the year of the sun (ie the cycle of the Earth revolving around the Sun) as the standard. The most common is the calendar (calendar) with a year lasting 365 days, a profit year 366 days, an average of 365.2425 days per year (due to the profit rule: 97 years in a 400-year cycle).
The lunar calendar is based on the lunar month, which is the cycle of changes of the lunar phases. This type of calendar does not take into account the movement of the Earth around the Sun, with only 354 or 355 days per year.
The lunar calendar is a type of lunar calendar. The number of days in each month is determined according to the lunar cycle. The day without a moon is called "soc", the day with a full moon is called "voice".
An average of 29.5306 days per lunar month is ance, so there are only 29 or 30 days per lunar month. In which, the 30th day is called the " full moon", the 29th day is the "less common month".
Notably, because the number of days in a month must be the whole, the lunar month is sometimes a short month (29 days), sometimes a full month (30 days). The arrangement of full months and missing months does not comply with the fixed law of one full month - one short month, but may have many full months or many consecutive months of lack. This must be based on accurate astronomical calculations.
According to the lunar calendar rules, the first day of each month is determined by the time of the "warming" event. Experts give an example: if the monsoon occurred at 23:59, the lunar month would be one day shorter. But if the morning falls at 0:01, that month will be one more day. Just 1-2 minutes difference is enough to decide whether New Year's Eve is the 29th or 30th of Tet.
In 2025, the fruit tree will fall at 8:36 p.m. on January 29, the first day of the Lunar New Year. The previous Soc appeared at 6:27 a.m. on December 31, 2024, the first day of the 12th lunar month. The period from December 31 to January 28 only has 29 days, so December of the year of the Dragon is a short month, and New Year's Eve to welcome the year of the Snake only has the 29th day of Tet.
Thus, in the 8 years from 2025 to 2032, the 30th day of Tet will be absent consecutively. This year's Lunar New Year of Binh Ngo 2026 will also not have a 30th day of Tet because it falls in this year's series.
However, whether December has 29 or 30 days, Vietnamese people still consider the last day and the last moment of the Lunar calendar as a sacred moment of transition between the old year and the new year, called New Year's Eve.
Therefore, during the years of December, many people still have the habit of calling the 29th of Tet the 30th of Tet, because "30th of Tet" has become the concept of the last day of the Lunar calendar year.
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