You might have noticed something odd in this year's Chinese calendar: the Year of the Snake has 384 days.

Wait a minute, isn't a year supposed to be 365 days?

Upon further inspection, this disparity isn't an isolated case! In fact, 2024, the Year of the Dragon (甲辰龙年), only had 354 days — 12 days less than the Gregorian calendar year.

So why the difference between the Chinese calendar and the Gregorian calendar?

In the Gregorian calendar, an average calendar year is 365.2425 days long, which is approximately the time it takes for the Earth to orbit around the sun. It is rounded to 365 days.

But what about the leftover 0.2425 days? To bridge this gap, the Gregorian calendar introduced the "leap year".

Leap years generally occur every four years. For example, the number 2024 is divisible by four, so the year 2024 is a leap year with 366 days. In contrast, 2025 is not divisible by four, so the year 2025 is a common year with 365 days.

In contrast, the Chinese calendar, which is a lunisolar calendar, combines the movement of the sun and the moon and is closely linked with the phase of the moon.

A synodic month (朔望月 in Chinese) begins when the moon aligns with the earth and the sun, marking the start of a new lunar month. Each "lunar cycle" lasts about 29.53 days. A standard lunar year has 12 months, totaling 354 days — a full 11 days shorter than the 365-day tropical year.

A typical year of 12 months needs to be supplemented with one intercalary or leap month every two to three years in the Chinese calendar. In the Chinese calendar, there are seven leap months in every cycle of 19 years.

And the Year of the Snake has such a leap month, bringing the total number of days to 384.

To summarize: While the Gregorian calendar follows a simple leap year pattern with an extra day added every four years, the Chinese calendar adjusts its months based on both lunar and solar cycles.

In most Gregorian calendar cases, a leap year occurs every four years. 2024 is a leap year because it is divisible by 4, while 2025 is a regular year with 365 days.

In the Chinese calendar, the Year of the Snake is a leap year, lasting 384 days — 19 days longer than the 365-day Gregorian year.

By accurately capturing the rhythms of the sun and moon, Chinese ancients not only enhanced agricultural productivity but also created a system that resonates with cultural and natural harmony to this day.