Often called lunar mansion, a lunar station or lunar house is a segment of the ecliptic through which the Moon passes in its orbit around the Earth. The concept was used by several ancient cultures as part of their calendrical system.
“In general, though not always, the zodiac is divided into 27 or 28 segments relative to the vernal equinox point or the fixed stars – one for each day of the lunar month. (A sidereal month lasts about 27+1/3 days.) The Moon's position is charted with respect to those fixed segments. Since the Moon's position at any given stage will vary according to Earth's position in its own orbit, lunar stations are an effective system for keeping track of the passage of seasons.
Various cultures have used sets of lunar stations 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 does not use stations, but each zodiac sign covers two or three. The Chinese system groups houses into four groups related to the seasons.
The concept of lunar stations is thought to originate in Babylonian astronomy.123 Tester (1987)4 explains that they appear in Hellenistic astrology in the 2nd-century list of fixed stars in the Katarchai by Maximusb, the Arabic lists by Alchandri and Ibn Abī l-Rijāl, and a similar Coptic list with Greek names.
Tester believes that though they were known in the Vedic period of India, all lists "seem to betray" transmission through Greek sources. Though pointing out that the Babylonians had well established lunar groupings by the 6th century BC, he also notes that the 28 station "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.”