Analogy between planets and days of the week in Japanese

Yesterday I discovered something that is so obvious, but which had never crossed my mind. In Romance languages (except Portuguese) most days of the week are dedicated to Roman gods, as in Spanish lunes (Monday, day of the moon), martes (Tuesday, day of Mars), miércoles (Wednesday, day of Mercury), jueves (Thursday, day of Jupiter), viernes (Friday, day of Venus), sábado (Saturday, the Sabbath), domingo (Sunday, day of the Lord). The planets in European languages are also dedicated to Roman gods (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune). What I found out yesterday is that Japanese, albeit non-European, names planets just like European tongues and follows the same pattern as most Romance languages' days of the week. Mercury (related to miércoles in Spanish, Japanese 水曜日) is 水星 (literally, water star), Venus (related to viernes, Japanese 金曜日) is　金星 (literally, gold planet), Mars (related to martes, Japanese 火曜日) is 火星 (literally, fire star), Jupiter (related to jueves, Japanese 木曜日）is　木星 (literally, tree star), Saturn (related to Saturday, Japanese 土曜日) is 土星 (literally, soil star), Uranus and Neptune aren't related to the days of the week, the former is 天王星　(the first character means sky, heaven) and Greek ουρανός (ouranós) means the same thing, and the latter is 海王星　(the first character means sea, and Neptune was the god of the sea).