For example, why is the solar term date in 158 1 different from that in the encyclopedia?

Because solar terms are a matter of the lunar calendar and have nothing to do with the Gregorian calendar.

The lunar calendar nominally calculates the period of the moon, but in order to guide agricultural time and other convenience, there is a leap month setting, which is consistent with the actual solar year.

The Gregorian calendar is theoretically calculated according to the solar year, but there is an error before 1582 (leap year is not set), so that there is an error of more than ten days when the Gregorian calendar is set to 158 1.

So in 1582, Pope Gregory directly modified the Gregorian calendar rules and erased 10 days, making the Gregorian calendar look like it now. By the way, the time is basically determined by applying the 24 solar terms that are strictly divided according to the solar year.

So 158 1 this year, you are looking at the old calendar with the biggest deviation from the new Gregorian calendar, so the solar terms are the biggest difference from the current time.