Zodiac celestial coordinate system, or more specifically an ecliptic coordinate system, which takes the ecliptic as the origin of latitude and the Sun's position at vernal equinox as the origin of longitude. The English word ' derives from ', the Latinized form of the Ancient Greek "zōidiakòs kýklos" (), meaning "cycle or circle of little animals". "Zōidion" () is the diminutive of "zōion" (, "animal"). The name reflects the prominence of animals (and mythological hybrids) among the twelve signs. The zodiac was in use by the Roman era, based on concepts inherited by Hellenistic astronomy from Babylonian astronomy of the Chaldean
Regina Coeli recited in place of the "Angelus" during the Easter season, from Easter Sunday until Pentecost. As with many Christian prayers, it takes its name from its incipit or first word(s). The Latin word "coelum", meaning "heaven" (hence the English word "celestial"), was a common medieval and early modern spelling of "caelum", which was the only form in Classical Latin. In medieval Latin, "ae" and "oe" were both pronounced [eː]; the form was also influenced by an extremely dubious etymology from Greek "koilos", "hollow". While the authorship of the "Regina Caeli" is unknown, the hymn has been traced back to the