The seven days of the week seems to be commonly named after celestial bodies. What I find curious is that all seven days apparently share the same names in both West and East.
- Sunday is, of course, Sun's Day. In East Asia, it is
日曜日- Day of the Sun.
- Monday comes from "Moon's Day". In East Asia, it is
月曜日- Day of the Moon.
- Tuesday is Mars / Týr's day. In East Asia, it is
火曜日- Day of Mars.
- Wednesday is Mercury / Odin / Wodin's Day. In East Asia, it is
水曜日- Day of Mercury.
- Thursday is Jupiter / Thor's Day. In East Asia, it is
木曜日- Day of Jupiter.
- Friday is Venus / Frigg / Freyja's Day. In East Asia, it is
金曜日- Day of Venus.
- Saturday is Saturn's Day. In East Asia, it is
土曜日- Day of Saturn.
The choice of planets probably reflects their higher visibility. But this doesn't explain why they are ordered the aforementioned way. So, is there an astronomical reason for this specific order? And does it explain the apparent agreement between Europe's and the Sinitic cultural sphere in naming their weeks - or did it come about due to cultural diffusion / pure coincidence?
(Note: I used Japanese for the Asian examples, but Korea shares the same system. Traditional Chinese did too, but Monday through Saturday was simplified to "Star Day 1-6" in Modern Chinese while Sunday remained the Sun's.)
@LieRyan has raised some evidence supporting the idea that the order became globalised due to cultural diffusion. So this just leaves the question of why the order is the way it is.
: Interestingly, one of the linked sources noted that the order of the five planets differed from classical Chinese ordering of elements. While true, it is actually the reverse of the (different, but more common) traditional order.