You may hear on the news, "July 7, today is Tanabata!" In Hokkaido, Tanabata is generally celebrated on August 7. Some Hokkaido residents may have wondered, "Why is it different only in Hokkaido?" Some people in Hokkaido may have wondered "Why is it different in Hokkaido?

As a matter of fact, some parts of Hokkaido, such as Hakodate and Nemuro, hold Tanabata in July and July, while the Sendai Tanabata Festival in Tohoku is held in August. Why are these differences created?

Why is Tanabata held on July 7 in the first place?

Tanabata is a star festival that was introduced to Japan from China in ancient times. It is a festival that started from a legend that "Star Orihime" and "Star Hikoboshi", who face each other across the Milky Way, can meet only on July 7.

On summer nights, the "Summer Triangle" of three stars, Vega, Altair, and Deneb, can be seen in the eastern sky. Two of the stars that make up the triangle are Vega, the first-magnitude star in the constellation Lyra, the "Orihime" or "Princess Orihime," and Altair, the first-magnitude star in the constellation Aquila, the "Hikoboshi" or "Checkers. These stars look especially beautiful on July 7, which is why this legend was born.

The reason is the difference between the "lunar calendar" and the "new calendar

Tanabata was originally held on July 7, but the reason why it is held in August in many areas in Hokkaido is due to the difference between the "old calendar" and the "new calendar. The solar calendar was adopted as the new calendar in November 1872 during the Meiji period (1868-1912), which caused the date to shift about one month compared to the old calendar.

The regions where the Tanabata festival is held on July 7th still keep the date of July 7th in the old calendar and hold it on July 7th in the new calendar even after the new calendar is adopted. On the other hand, in the area where "August 7th is Tanabata day", since "July 7th" in the lunar calendar corresponds to "August" in the new calendar, they keep only "7th", the day when Tanabata was originally held, and hold it on "August 7th", a month later than the original date.

Incidentally, the reason why Obon is also held in July in some areas and in August in others is due to the difference between the lunar calendar and the new calendar, just as in the case of Tanabata. In Hakodate and Nemuro, both Tanabata and Obon are held in July.