Day. The Romans originally used an eight-day week with each day named after the planets. They switched to a seven-day system with each day named after the gods. They had a fiendishly complex calendar. On Gaea, the calendrical system hailed from Atülän until the Council of Wizards established the Doctrine of Unity. Dies Solis — /ˈdi.es ˈso.lis/ (DEE-es SOH-lis) The Day of the Sun. Sunday. Dies Lunae — /ˈdi.es ˈlu.nae̯/ (DEE-es LOO-nah-ee) The Day of the Moon. Monday. Dies Martis — /ˈdi.es ˈmar.tis/ (DEE-es MAR-tis) The Day of Mars. Tuesday. Dies Mercurii — /ˈdi.es mɛr.ˈku.ri.i/ (DEE-es mer-KYOO-ree-ee) The Day of Mercury. Wednesday. Dies Iovis — /ˈdi.es ˈjo.wis/ (DEE-es YO-wis) The Day of Jupiter. Thursday. Dies Veneris — /ˈdi.es ve.ˈne.ris/ (DEE-es veh-NEH-ris) The Day of Venus. Friday. Dies Saturni — /ˈdi.es sa.ˈtur.ni/ (DEE-es sah-TOOR-nee) The Day of Saturn. Saturday.