四象 Si Xiang – Four Images
What are the four images Sì Xiàng (四象)?
(四象 Sì xiàng) doesn’t mean four elephants or shapes, but it refers to four Chinese giant astronomical constellations that divide the sky (celestial equator) into four equal sectors, also called quadrants.
The two equinoxes and two solstices are indicators of the beginning of the four seasons in a year. Four phases of the moon and four stars at the ecliptic mark the two equinoxes and two solstices, which divide the sky into four seasons and four sectors. Each of the sectors covers one constellation, namely:
東方青龍 Azure Dragon
for the spring
equinox (between March 19 and 21),
南方朱雀 Vermilion Bird
for the summer
solstice (between June 20–22),
西方白虎 White Tiger
for the autumn
equinox (between September 21 and 24) and
北方玄武 Black Tortoise
for the winter
solstice (between December 20 and 23).
Only one constellation can be entirely seen in any given season. The four constellations bear the asterisms of the (十天干 Shi Tian Gan) the 10 Heavenly Stems
, (十二地支 Shí'èr dìzhī) the 12 Earthly Branches
, and (二十八宿 Èr shí bā xiù) the 28 Lunar Mansions
. What are The 28 Lunar Mansions (二十八宿 Èr shí bā xiù)
On average, the period of revolution of the moon around the earth in reference to a fixed star is almost 28 days (27 days, 7 hours, and 43 minutes of mean solar time).
Each of the four quadrants or sectors consists of an unevenly distributed 7 and, in total, 28 asterisms (star clusters). These 28 sectors, which are passed by the moon along the ecliptic, are called 二十八宿 (Ershi Ba Xiu), the 28 Lunar Mansions or Lodgings.