I am not American. Just because other people break the rules, there's no reason why I should, and definitely no reason why my teacher should say I was wrong for insisting that Earth is the name of the planet we live on, the other planets' names are capitalized and therefore Earth's name should be capitalized.You guys aren't getting what I'm saying about English and sense. You are right that the rules of English dictate that our planet be referred to as Earth, and that the ground be referred to as the earth. However, it is still correct to use the latter term for the planet, because English breaks its own rules without shame.
(It may just be an Americanism, but I've definitely seen it.)
But this was a teacher who insisted that trees "loose" their leaves in the fall, and there were other instances of where she was wrong, was called on it, and was loathe to admit that a student was right. That year was one long squabble, as I'd just recently become a Star Trek fan and my interest in astronomy was rekindled... both of which meant that I slanted as many of my assignments in that direction as I could.
Just think... if the internet had been around then, I'd have had other Star Trek fans to talk to, rather than taking my writing efforts out on a teacher who knew little about science, cared even less, and was allergic to admitting to making mistakes.
Revenge was sweet, though. One of our assignments was to take a nursery rhyme and rewrite it as a news story. We were supposed to read it out loud to the class, but the teacher said that she understood that some of us were shy about doing that, so she would read those out loud herself, if we asked.
So I wrote the Peter Piper rhyme into a news story, and it was as much of a tongue-twister as the original rhyme (all the sentences were grammatically correct and made sense). I asked her politely if she would please read mine to the class, and after the second sentence, if looks could kill I'd have become a puddle of goo right then and there. The other kids thought it was a hoot.
I'll admit that it was a dirty trick to play. But after all the unnecessary crap she'd put me through that year, docking marks for nonexistent mistakes, I thought she deserved it.
Whut?Absolutely but not just that. "The Earth is the only chance our species has for survival" refers to the planet and would be gibberish without the article. Whenever we refer to the planet on which we live we use "The". Even if we substitute the word "world" our planet is very much the definite article. The World was, after all, Not Enough".

"Earth is the only chance our species has for survival" is not gibberish in any way. Of course if "world" were substituted, we would need to write "The world" because our planet's name isn't "World." But using "world" is awkward and inaccurate, because it makes me want to know which world. This one? Some other one? Be specific.
Break it over your knee, and you'll have two twigs. Problem solved. Otherwise, the only applicable word I can think of is "stick."Here's an example that fell in my path the other day. I was walking my dog after a windy day and I saw part of a tree blown down before me. It was about three feet long and about half an inch in diameter at its thickest part. It felt too big to call it a twig. But it also felt too small to call it a branch, since the main branches on the tree it fell off of were maybe 8 inches in diameter at the place where they met the tree. Of course, one can name it in English; one can call it a small branch or a large twig. But a language that had a word for that intermediate stretch would be able to think this thing that I saw in front of me a little more precisely than English can.