Mars:
Sand day.
We’re being invaded by Earthlings day.
We’re Earths garbage dump day (alternate celebration).
Mercury:
Everyday is New Year’s Day (a day is longer than a year on Mercury.)
Burnt to a crisp day.
Venus:
It’s too hot to celebrate day/year.
Jupiter:
Pass the beans day.
Get hit by a comet day.
There’s another new moon day.
Saturn:
Just how many moons are there? day.
Another earth space craft is heading our way day.
I lost count of the moons day.
Uranus:
Do we still have rings? day.
Is it cold or is it just me? day.
Neptune:
We’re closer to the sun than Pluto day.
We’re further from the sun than Pluto day.
Pluto;
We’re not a planet anymore day.
We’ve seceded from planet hood day (alternate holiday).
We’re closer to the sun than Neptune day.