Dictionary.com Word FAQs
When do I capitalize the word earth?
If you are talking about the Earth as a proper noun, as a planet or celestial body, then you can capitalize Earth and use no article (the): How far is Earth from the Sun? But it is also fine to leave it as lowercase and use the with earth if you are talking about it as the planet we live on: The earth rotates on its axis. It is ok to do the same with the sun and the moon. When you are talking about the ground or soil as a surface or stratum, then you must lowercase the word: The archaeologists excavated the earth at the site. The word earth is derived from Greek era. Here is something interesting - we never hear people say the Mercury, the Pluto - but we do say the Earth, the Moon. Using the definite article "the" in front of an uncapitalized "earth" has its roots in the worldview that we are separate from and fundamentally different. (P.S. There is a town called Earth, Texas.)