Zodiac calculation system of Tiangong map

Because astrology originated and developed in lower latitudes (Babylon, India, Greece), the earliest palace system-the whole palace system was to divide the zodiac into the zodiac equally. However, this division is increasingly difficult to reach high latitudes. The most extreme example is that in the polar circle, during the polar day and night, the ecliptic and the horizon do not intersect. In the process of astrology spreading to high latitudes, astrologers created various palace systems to adapt to this situation. However, there is no satisfactory solution to the problem of palace division in extremely high latitudes.

The whole constellation system: each constellation is opposite to a palace. This is the oldest system.

Flat palace system: every 30 degrees from the rising point.

Alcabitius: The right ascension from the ascending point to the meridian is divided into three equal parts, and the projection on the ecliptic is 10, 1 1 2; Divide the right ascension into three parts from the descending point to the bottom of the sky, and project it onto the ecliptic to form 1, 2, 3 houses.

Reggio Montanus Palace System: Divide the celestial equator into 12 on average, and project it on the ecliptic with the north-south horizon as the axis.

Placidus Houses system: At present, the most common system in western astrology is to allocate according to time rather than space. Only applicable between 66 degrees north and south latitude.

Kochhouse system: an extension of plessy's system.