10 letters.
I could talk a bit about language as image and stuff, and if you ask me in the comments I'll try (or some other time), but for now I'll let this little piece stand for itself... except I will mention that Earthlight is the title of a
science fiction novel by
Arthur C. Clarke and that I likely got the word from there, though it's been so long that I can't say for certain. Haven't read the book.