I recenty got my essay back from my teacher and she said that it was wrong to use upper case "Earth". When I'm writing Earth, I'm referencing to the planet Earth, not soil. This is the sentence which included "errors". She gave me an error in every word that I marked with strong first letter.

This is why the Moon orbits the Earth, and the Earth orbits the Sun, and the Sun orbits the black hole in the middle of the Milky Way.

Who is right, me or her?


When talking about the planet Earth, it is a proper noun and is always capitalized. When talking about soil, or dirt, then earth is not capitalized (except when used as part of a title).

Your example sentence is correct. Another example if you need more proof, but there are many more on Google.

Another example using "earth"

[Edit] Apparently some editors are lazy. In common usage, the name of the various celestial bodies is often not capitalized (possibly because apparently it's too hard to reach the "Shift" key). Such is the evolving nature of English in a technological age, lol.

Anyway, this might be a better example -- although I would look specifically at the responses by the "experts" and not the questions themselves.

So a more comprehensive answer is that while perhaps Earth should be capitalized when talking about the planet itself, it often is not. It also may not be capitalized when talking figuratively about a large region of the planet, e.g. "his empire stretched from one side of the earth to the other", or in an idiom like "to the ends of the earth".

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    Not necessarily. Earth (the planet) can be treated as a proper noun or a common noun. Preceding 'earth' with the means we are no longer referring to the planet by name, but rather, as the land surface of the planet. – mike Jan 6 '17 at 17:22
  • I'm not sure I agree. "The Earth" in this context strikes me as being rather like "the Jupiter", which is clearly wrong. Also, your second example uses "Rare Earth" in title case; in the body of the article, "rare earths" is not capitalized. – verbose Jan 6 '17 at 17:23
  • @verbose yes which is why in my answer I specify that "earth" as "dirt" can be capitalized as part of a title, e.g. "We are Naught but Earth" – Andrew Jan 6 '17 at 17:31
  • My disagreement is with your statement that the OP's example sentence is correct. I agree with @mike that if preceded by "the", earth should not be capitalized. The reason for flagging your second example is that it would likely be confusing to an English language learner that "earth" is capitalized in the title if the point of the example is that "earth" is not capitalized. – verbose Jan 6 '17 at 18:22
  • @verbose I understand your point, but see my second example. Note that some of the experts capitalize "the Earth" (as well as the Moon and the Sun), and some do not. While I think it's just laziness in typing, others might feel as you do. However also note there is nothing wrong with using "the" with a proper noun: "the White House", "the Statue of Liberty", "the Grand Canyon", etc. – Andrew Jan 6 '17 at 18:39

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