Zoiac 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, from the Greek ζῳδιακός [κύκλος], meaning "circle of animals", derived from ζῴδιον, the diminutive of ζῷον "animal". 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.