Why Not "Earthian"?

While we all have varying degrees of experience with Martians, or at least with the word "Martian," the question remains: Why aren't we Earthians? In science fiction films dating back to the first extraterrestrial encounters, inhabitants of this planet are called Earthlings (ofttimes condescendingly), whereas those from other bodies use the -ian suffix (including those from Avatar's Pandora: Pandorians).


The following list presents common references to either individuals, items, or properties of other bodies in our solar system (note the suffixes, more complete list here):

Mercury: Mercurian, Hermean
Venus: Venusian
Earth: Earthling
Mars: Martian
Jupiter: Jovian
Saturn: Saturnian
Uranus: Uranian
Neptune: Neptunian
Pluto: Plutonian [Yes; I included Pluto]

To answer the question [finally], Earthlings are called Earthlings because it is a diminutive form (Wikipedia!).

Not satisfied? [And you shouldn't be.]

The definition to the suffixes -ling and -ian could be "one connect with," and "of, relating to, or resembling," respectively. Considering this, Earthian should be accepted, albeit not commonplace; therefore, perhaps the best answer to the question is "just because." Common use dictates that it is such.

And don't you forget it, Earthling!