The Romans, during late antiquity, named the days of the week after their gods and corresponded to the five known planets plus the sun and moon. In the order of Sun, Moon, Mars, Mercury, Jupiter, Venus and Saturn. The Chinese naming system for the days of the week is similar to that of the western system and is derived from the seven luminaries (七曜) visible to the naked eye. The Chinese also had adopted the seven-day week from the Hellenistic system from the 4th century.
Sunday is "Sun's day", 日 (太陽星)
Monday is "Moon's day" 月 (太陰星)
Tuesday is Tiw (or Tyr). He is equated to Mars, the Roman war god. 火星 (熒惑星)
Wednesday is (W)Odin; the Romans connected (W)Odin to Mercury. 水星 (辰星)
Thursday is Thor, the Norse god of thunder. The Roman connected Thor to Jupiter.木星 (歲星)
Friday is named after Frigg; she is with Venus, the Roman goddess. 金星 (太白星)
Saturday is “Saturn’s day.”土星 (鎮星)
