[Verginius Rufus]

Do all the planets have a day?

Interesting thought. Congress has been sitting every year since 1789 and has never dealt with the issue.

For Uranus, Neptune, and Pluto, their day could be the date they were discovered by human beings. Venus obviously gets February 14th. Mars already has a whole month (March). That leaves Mercury, Jupiter, and Saturn needing attention.

[Verginius Rufus]

In terms of the days of the week, Mars, Mercury, Jupiter, and Venus already have the days Tuesday to Friday named for them in French, Italian, Spanish and Romanian, and English "Saturday" got its name as the day of Saturn.

(The English names for Tuesday, Wednesday, Thursday and Friday come from substituting Germanic names of deities for the Roman names of deities--the particular assignment of a day to a god/planet goes back to astrology where the planets took turns controlling hours and each day was named for the planet controlling the first hour of that day.)