Astrology: Zodiac

Zodiac denotes an annual cycle of twelve stations
along the ecliptic, the apparent path of the sun
across the heavens through the constellations that
divide the ecliptic into twelve equal zones of
celestial longitude.

The zodiac is recognized as the first known
celestial coordinate system.
Babylonian astronomers developed the zodiac of
twelve signs.The etymology of the term zodiac
is that it comes from the Latin zōdiacus,
and from the Greek meaning 'circle of animals'.

However, the classical Greek zodiac also includes
signs (also constellations) that are not represented
by animals (e.g., Aquarius, Virgo, Gemini and for
some Libra).

Another suggested etymology is that the Greek
term is cognate with the Sanskrit sodi,
denoting "a path", i.e., the path through which
the Sun travels.

The zodiac also means a region of the celestial
sphere that includes a band of eight arc degrees
above and below the ecliptic, and therefore
encompasses the paths of the Moon and the naked
eye planets (Mercury, Venus, Mars, Jupiter, and Saturn).

The classical astronomers called these planets
wandering stars to differentiate them from the
fixed stars of the celestial sphere (Ptolemy).

Astrologers understood the movement of the planets
and the Sun through the zodiac as a means of
explaining and predicting events on Earth.