I Didn't Make the Rule

Today I'm venting!

As a grammar teacher, I have to teach certain rules. Sometimes the rules make sense, and sometimes I just shake my head. (I do a lot of shaking with spelling!)

I'm still going to include the planet Pluto (although it was demoted as a planet), but just let me say that all the planets, except earth, are capitalized. Earth, for some strange reason, isn't unless it begins a sentence or is listed with other heavenly bodies. The same is true with the words moon and sun.

Yes, it's weird. It is the name of the specific planet, but some dead guy designed this rule. There are two ways I try to make it clear to my students.
1) We don't capitalize the word home, and since earth is our home planet, don't capitalize it.
2) With the exception of earth, all the other planets are named after Roman gods. They are names, and they know to capitalize names! (Mercury/Hermes-messenger god; Venus/Aphrodite - goddess of love; Mars/Ares-god of war; Pluto/Hades-god of the underworld; Neptune/Poseidon-god of the sea; Uranus-original/creator god-overthrown by son Saturn/Cronus; Jupiter/Zeus-ruler of gods-overthrew his father, Cronus.) Sorry, no god named Earth. The goddess of the earth was called Gaea. Why we don't call this planet Gaea instead, I don't know.

It irks me to no end when the science teacher gives my students a twenty minute lecture telling them that I'm wrong. That's like me teaching science and trying to correct her.
G-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-r-!!!!!!!!!

Suggestions, anyone?