When did the term “Earthling” come from?

Though people associate it with very old science fiction, you won&rsquo;t see any occurrence of the term in its current meaning (a human inhabitant of the planet Earth, as opposed to an extraterrestrial) prior to 1949. Actually, the term was first used by the Old Man himself, Robert E. Heinlein, in his 1949 novel &ldquo;Red Planet&rdquo; (a novel remembered for a weird digression where they…