The days of the week are named after the seven classical planets or the gods associated with them.
Tuesday Mars (Mardi)
Wednesday Mercury (Mercredi)
Thursday Jupiter (Jeudi)
Friday Venus (Ventredi)
I’ve given you the French to help out with some weekdays.
I know the Sun and Moon aren’t planets but they are as far as the ancients understood the term.
7 planets, 7 days of the week.