2024 has just begun. Careful netizens on both sides of the Taiwan Strait were surprised to find that the date and week of 2024 are consistent with the 1996 calendar. They joked that "the old calendar can be reused, which is environmentally friendly and saves money."
According to Taiwanese media reports, sharp-eyed netizens discovered this "mysterious coincidence": when they opened the new calendar for 2024, they found that the date and week of the Gregorian calendar were exactly the same as 28 years ago in 1996. Is this a coincidence or is there a pattern?
Taipei Planetarium research team leader Xie Xiangyu explained that this is because a leap year occurs every four years, which combines with the 7-day week to form a 28-year cycle. The last time this same cycle occurred was in 1996, which was also a leap year and January 1st was also a Monday.
Simply put, there are 365 days in a year, which is equivalent to 52 weeks and 1 day. Therefore, the same day in the next year will be "added 1 (day)" to the week. If it is a leap year, there will be 365 days in a year. 366 days, then on the same day next year, 2 days will be added to the week. There is a leap year every four years, so the week numbers will move forward by 5 days in four years. Then after 7 four years, the week numbers will move forward by 35 days in total, which is an integer multiple of 7. Therefore, 28 years later will appear. , the week number completes a cycle.
However, experts emphasize that the above algorithm is only calculated at a mathematical level. In fact, it needs to be explained at the level of astronomical calendar. This algorithm only applies within 100 years, because in the calendar, to be precise, a year is 365.242199 days, which means that there will be 3 more days every 400 years. In the calendar, It should be corrected by "setting leap". Therefore, between 2000 and 2099 AD, the Gregorian calendar date cycle of 28 years was applicable. In other words, the next time this happens will be in 2052.
However, although the Gregorian calendar date distribution is exactly the same, a closer look will reveal that the lunar calendars of 1996 and 2024 are very different. For example, the Spring Festival in 2024 will be on February 10, while the Spring Festival in 1996 will be on February 19.
The Gregorian calendar is the solar calendar. It is a calendar determined according to the rotation of the earth around the sun. Since the earth's revolution is 365.2422 days, which is longer than our average year of 365 days, there will be an extra day every four years. This day is February 29 in leap years. day.
Different from the Gregorian calendar algorithm, the lunar calendar is based on the moon's waxing and waning cycle. A synodic month is about 29.53 days, and the whole year is generally 354 days or 355 days, which is 11 days less than the Gregorian calendar year. The lunar calendar is also divided into leap years and flat years. An ordinary year has twelve months and a leap year has thirteen months.
Source: Standing Sea
