January 29, 2025 – Eastern New Year. Secrets of the lunisolar calendar

According to the eastern calendar, the new year of the Wood Snake will come on January 29. However, this holiday falls on a different day each time, within a certain date range. It is connected with what happens with the Sun and the Moon.

Chinese New Year

Chinese calendar

The year 2025 is often called the year of the Wood Snake, referring to the Eastern horoscope, where 12 animal signs form a combination with 5 elements, thanks to which we have such bright names. However, it is not true, because the same Chinese tradition says that the year with this name should begin on January 29.

Generally, the onset of the Eastern New Year is not constant relative to the Gregorian calendar dates. In different years, the solemn Chūnjié Day, whose name translates as “Spring Festival,” may occur between January 21 and February 20.

The reason for this is that the calendar by which it is celebrated is not a solar calendar like the Gregorian calendar, but a lunisolar calendar. That is, it takes into account not only the equinoxes and solstices but also the changing phases of the Moon.

Chūnjié Festival in China. Source: www.ncabgroup.com

Actually, by definition, the Spring Festival, or, as we call it, the Chinese New Year, comes during the first phase of the new Moon, at the end of the first full lunar cycle after the winter solstice.

It sounds confusing, but in practice, it’s not that complicated. There is the winter solstice, the longest night of the year. In 2024, it was December 21. Then you have to wait for the phase of the new Moon, that is, it will not be visible. This time it happened on the night of December 30 to 31. It was the so-called Black Moon, but already by tradition, which has nothing to do with China. Next, the Moon should begin to grow and there will be a full moon. In 2025, it came on the night of January 13-14, after which the Moon began to decrease.

And at the moment when it disappears again, turning to us with its shaded side, the Chūnjié holiday, the Eastern New Year, will come. In China and countries culturally close to it on this day begins the winter cycle of holidays, full of traditions and rituals, many of which are well known to us. Families gather for a gala dinner, and fireworks and other pyrotechnics are set off.

Phases of the Moon. Source: www.findusoutside.org

“Heavenly Trunks” and “Earthly Branches”

It is possible to tell separately about how the names of years are formed, although this topic has nothing to do with astronomy. This system is based on the idea of 10 “Heavenly Trunks” and 12 “Earthly Branches”, the combination of which together forms a 60-year cycle.

It is easiest to deal with the “Earthly Branches”. These are the 12 animals of the Chinese horoscope, which are well known to us and form a sequence: Rat – Bull – Tiger – Rabbit – Dragon – Snake – Horse – Sheep – Monkey – Deer – Dog – Pig.

With “Heavenly Trunks” everything is a little more complicated, as they form pairs, in which one of the signs is identified with “yin”, and the other – with “yang”. In turn, “yin” and “yang” is a separate complex concepts from Eastern philosophy, which is not directly related to the cycle. In practice, it is important to realize that each of the pairs belongs to one of the five traditional Chinese elements.

Animals of the Chinese horoscope. Source: Wikipedia

Therefore here the alternation of the elements of years is as follows: first come the years to which correspond “Heavenly trunks” jiǎ and yǐ, to which corresponds the element of Wood, then two years – “fiery” bǐng and dīng, then – wù and jǐ, to which corresponds Earth, then – gēng and xīn, the element of which is Metal and, finally, “watery” rén and guǐ. After that, everything is repeated.

It can be seen that there can be 120 possible combinations of “trunk” and “branches” in total. However, since both 10 and 12 are divided by 2, half of them never happen. Therefore the cycle of the Chinese horoscope is 60-year and the years of one element go in pairs.

The cycle starts with the Wooden (jiǎ) Rat, then comes the Wooden (yǐ) Bull, then the Fire (bǐng) Tiger, Fire (dīng) Rabbit, Earth (wù) Dragon, and so on, until the Water (guǐ) Pig comes, after which the 60-year cycle will not start again. That is why the year of the Wood Dragon, which according to the Chinese lunisolar calendar is still in progress, will be replaced by the Wood Snake and replaced by the Earth Horse.

It is worth noting that from the point of view of the Chinese horoscope, it is the indication of the element, not the color, which is often used in ours, that is accurate. The point is that the elements are primary in this system, and colors, seasons, and sides of the world are secondary.

The five elements. Source: Wikipedia

And it is with colors in the Chinese horoscope that there is great confusion. The thing is that different traditions associate different elements with different colors. And if on Fire, Earth, and Metal there are no disagreements, then with Wood and Water there are big problems, because the colors of the first – green or blue, and the second – black or blue. It is easy enough to confuse blue with blue, but if green is associated with trees, then the correspondence of black and water is a rather unobvious thing.

Solar Chinese calendar

From all the above, one might get the impression that the Chinese calendar is more suitable for mystical rituals than for the accurate reckoning of time. From this, it is not too far to think that Eastern civilization in general is less inclined to exact knowledge than European civilization, but this is not so.

The point is that all of the above describes only one of several systems of counting time that have been used in China for thousands of years – the Hsia lunisolar calendar. It is extremely ancient but very popular to this day. However, there was, for example, the calendar of the Qin dynasty, which was used in the 3rd century BC, and in it, the beginning of the year was considered the last new moon before the winter solstice. And the year was already divided into seasons, which were calculated without regard to the phases of the Moon.

How is the problem with the year lasting an unequal number of days solved.
Source: www.timeanddate.com

In general, the Chinese lunisolar calendar is not something unique. All nations began their counting of time with the observation of the Moon, then calculated the period between the solstices, realized that the year is not so easy to divide into lunar cycles, and tried to cope with it somehow. Before Julius Caesar in 45 BC introduced the calendar, on which Ukraine lived until the 20th century, all over the Mediterranean also used lunisolar calendars. Easter and Hanukkah with their erratic dates are a legacy of those times.

As for the Chinese astronomers, it is quite possible that they had a solar calendar, which was as accurate as the Julian calendar, even earlier than their Alexandrian colleagues. The fact is that in 104 BC the Tàichū calendar was introduced in China. The algorithm of its calculation is not described in the documents, but scientists have calculated that in it the year could be defined as 365.25, which is as accurate as the Julian calendar, but has a greater error than the Gregorian.

But there is no doubt about the two solar calendars adopted in the first century AD. They had the same accuracy as the Julian calendar. It is known that they were calculated by Chinese astronomers based on what in Western science is called the Metonic cycle.

Chinese solar calendar. Source: www.thatsmandarin.com

The point is that the periods of rotation of the Moon around the Earth and the Earth around the Sun can still be “friended” between them. For 19 solar years, there are 235 lunar cycles. Knowing this value, ancient astronomers created solar and lunisolar calendars.

It is also known that in 223 AD in one of the kingdoms that then existed on the territory of modern China, a solar calendar was introduced, where the duration of the year is 365.2462 days. This value is closer to a real tropical year (its duration varies within a few seconds) than the Julian calendar, which was then used in Europe. Only the Gregorian calendar, developed in the 16th century, surpassed it in accuracy.

Which calendar is better?

So why in the East continue to use such an imperfect Hsia calendar for calculating the time of advent, if for 2000 years they have a much more accurate solar calendar? The fact is that during all this time in the East, solar calendars were predominantly used by court astronomers. It was knowledge that was not trusted by everyone, but it was used to accurately divide the year into 24 seasons. In each of them, one had to perform their agricultural work, which was what the government’s instructions proclaimed.

New Year’s Eve celebrations in a Chinese village. Source: cnn.com

And people in their daily life continued to use not so accurate, but much more understandable and familiar Hsia calendar. After all, the time of the winter solstice is easy enough to track approximately, but quite difficult – precisely.

But the phases of the Moon can be observed by everyone. Therefore, every remote village could know when the Chūnjié Festival and the new year would begin without any imperial orders. It was enough to just look at the sky and watch the Sun and Moon with a little bit of attention.

Provided by phys.org

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