Why does Taurus go from April 2 1 to May 2 1?

According to the book Birth Time and Destiny, April 2 1-May 21is not a fixed time in Taurus, but the exact time limit is Grain Rain-Xiaoman, which is a solar term. Every year, the solar term has an accurate time (people born on April 20 may be Taurus or Aries). For example, Hitler was born at1April 20th, 889 18: 30. At this time, the sun just entered Taurus Palace, so it is Taurus Palace. People's personality is more related to the rising constellation of birth time (hours), so we can't just look at the month. Taurus: 2 1-2 1 When the date is early or late in May, you can accurately judge your constellation by looking at the exchange day of the year.