If something fell out of Mars' sky onto the Martian surface, would it have "crashed to earth"? [closed]

This is surprisingly complicated!

The first thing to say about it is that the phrase crashed to earth almost did not exist before technological flight; the hits that Google Book Search claims to find from the 19th century are almost all scanner errors for "crushed to earth". I did find one real example of a "Castle" [sic] crashing to earth in a poem from 1870, but even so, I think this is enough to suggest that a pre-flight society might not think of something falling out of the sky in quite those terms. ("Fell to earth", by contrast, has existed for much longer.) So your friend may wish to avoid it on that basis alone (assuming that the people of his/her story don't have that level of technology yet).

The second thing to say about it is that I think the phrase crashed to earth originally used "earth" more in the sense of "earth and sky" than in the sense of planet Earth. I say this in part because the planet has traditionally been called "the Earth" rather than simply "Earth". In fact, even today, with all of our knowledge and literature about other planets, "the Earth" is more common than "Earth" except in rather limited contexts, such as when another planet is mentioned at the same time. (Here is a Google Ngram Viewer chart showing that "revolves around/orbits/circles [the] Earth" nearly always has 'the', and that even "Venus and [the] Earth" preferred 'the' until the late 1970s: [link].) So to that extent, at least, your friend has a point.

But the third thing to say about it is that words' meanings evolve over time, and your friend is writing for a modern audience where you will not be the only one to find this usage jarring in a non-Earth setting. Some writers have started to capitalize "crashed to Earth" in recent years (see this Ngram chart), which clearly shows that they think of it as referring to the planet.

And since you mention Mars . . . in 1999, the Mars Climate Orbiter burned up in the Martian atmosphere due to a software error (numbers representing thruster force were produced by a module that assumed the unit was pounds and consumed by a module that assumed the unit was newtons). Technically it didn't actually reach the surface of the planet, but that wasn't clear at first, and anyway people are often imprecise about such things, so this is a natural experiment for how people might describe this (albeit not people living on Mars). There are plenty of pages saying that it had "crashed on Mars" or "crashed into Mars", but I can't find even a single instance of anyone saying it had "crashed to Mars" or "crashed to earth". (One page does say that it "crashed to Mars' surface", but that's not quite the same.) I think the non-use of "crashed to earth" suggests that even writers who write it with a lowercase 'e' are not necessarily comfortable applying it on planets besides Earth.

Unfortunately, I'm not sure how helpful the above is in terms of deciding what your friend should write instead of "crashed to earth". Mars is not a great model to follow; your friends' readers would probably find the equivalent of "crashed on Narnia" or "crashed into Middle-Earth" to be even more jarring than "crashed to earth".

So, I'd suggest that your friend use a slightly different phrase. There's a long tradition of fantasy writers using vaguely-archaic, not-quite-standard usages, in order to set their worlds off from the everyday; when done well, it can be quite effective. Maybe "crashed out of the heavens"? "Thundered into our midst"? "Fallen into our reach"? "Lost the sky"? "Been cast to the ground"?

Remember that in the narrative universe, no-one is speaking English, but the writer an English-speaking Earthman, is rendering it in English for the English-speaking Earthmen readers. If you were to transform the entire text to avoid Earth-centric metaphors and figures of speech, including those that rely on Earth animals, Earth plants and so forth, you would have a very alien body of text that would be hard and possibly unpleasant to read. Conversely, sprinkling alien, made-up terms can help establish the setting as fantastic or otherworldly. It's a matter of balance.

But for this specific turn of phrase, remember that since our English language evolved on the planet Earth, the word "Earth" has a complicated double meaning for us - it means the ground - any ground, but it also means the specific ball of mud we're sitting on. Just like sun means both "any star in space* but also "Sol, our specific star". That's why "crashed to earth" doesn't feel out of place to me in an otherworldly scenario. It's the Martian earth - but it's not Earth.