Days of the week
Let’s look at the day of the week the way you see in the calendar. Each kanji represents the day of the week from Sunday to Saturday.
S M T W T F S
日 月 火 水 木 金 土
にち げつ か すい もく きん ど
Days of the week is expressed by adding ようび (yōbi) at the end.
Kanji for the days of the week has some are related to Planet and Solar systems. 日 月 火 水 木 金 土
⁺ 太陽（たいよう）= the sun,
日（ひ、にち、じつ）= the sun, day, daytime
⁺⁺ 星（ほし）= star
Day of the week Sentences:
・きょうは なんようび ですか。(kyō ha nan yōbi desuka)
Which day of the week is it today?
・あしたは なんようび ですか。(ashita ha nan yōbi desuka)
Which day of the week is it tomorrow?
・あさっては なんようび ですか。(asatte ha nan yōbi desuka)
Which day of the week is it the day after tomorrow?
・きのうは なんようび でしたか。(kinō ha nan yōbi deshitaka)
Which day of the week was it yesterday?
・おとといは なんようび でしたか。(ototoi ha nan yōbi deshitaka)
Which day of the week was it the day before yesterday?
Post finder: Language guides to help with learning Japanese
Monday - moon day- lunes, lundi
Tuesday- fire day- Mars day- martes, mardi
Wednesday- water- Mercury- miércoles, mercredi
Thursday - wood- Jupiter- jueves, jeudi
Friday- gold- Venus- viernes, vendredi
Saturday- soil- Saturn- sabado, samedi
Sunday- sun day- (domingo, dimanche)
Why are they so similar to the French/Spanish days of the week? They're all named after planets in the solar system/Roman Gods whereas English and German days are named after Norse Gods.
So we have sun (日) - day and moon (月) day, which are consistent in both Japanese and English (and also Chinese and a few other languages somewhat). And then there's 火，水，木，金，土 (fire, water, wood, metal, and earth) which are also the five traditional Chinese elements, while English names them after Norse gods (with the exception of Saturday - Saturn). That's interesting though - they're named after the planets which are associated with Chinese elements? Cool
Anyway, if you're familiar with Chinese, it somewhat sounds similar:
火 - か (kind of like 开火 - kai huo)
水 - すい (the Chinese is pronounced shui)
木 - もく (kind of like 木头 - mu tou)
金 - きん (the Chinese is pronounced jin)
土 - ど (Chinese pronounced tu, or 土豆, tu dou)