Lunar mansion

A lunar mansion is a segment of the ecliptic (often called a station, or house) through which the moon moves in its orbit around the earth, often used by ancient cultures as part of their calendar system. In general, though not always, the zodiac is divided into 27 or 28 segments relative to fixed stars - one for each day of the lunar month, which is 27.3 days long - and the position of the moon is charted with respect to those fixed segments. Since the position of the moon at given stage will vary according to the position of the earth in its own orbit, the mansions of the moon are an effective system for keeping track of the passage of seasons.

Various cultures have used sets of lunar mansions astrologically; for example the Jyotisha astrological Nakshatras of Hindu culture, the Arabic manzils (manazil al-qamar), the twenty-eight mansions of Chinese astronomy, and the 36 decans of Egyptian astronomy. western astrology doesn't use mansions but each zodiac sign covers 2-3 mansions. The Chinese system groups mansions into four groups related to the seasons.

The concept of the lunar mansions are considered to be Babylonian in origin. Jim Tester, in his History of Western Astrology explains that they appear in Hellenistic astrology as the second century list of fixed stars of Maximus of Tyre, the Arabic lists of Alchandri and Haly Abenragel, a similar Coptic list with Greek names, and that though they were known in Vedic India, all lists "seem to betray" transmission through Greek sources. Though pointing out that the Babylonians had well established lunar groupings by the sixth century B.C., he also notes "the twenty-eight mansion scheme was derived via Egyptian magic by the linking of the lists of lucky and unlucky days of the lunar month with the hemerologies and with the zodiac".

The 28 Lunar Mansions (Chinese: , Èrshí-Bā Xiù) are the Chinese and East Asian form of the lunar mansions. They can be considered as the equivalent to the Western zodiac, although the 28 Mansions reflect the movement of the Moon through a sidereal month rather than the Sun in a solar year. In their final form, they embodied the astral forms of the Four Symbols: two real and two legendary animals important in traditional Chinese culture such as fengshui.

...
Wikipedia