When do you capitalize Earth, and when is it lowercase? 

Earth (capitalized) is used when referring to the name of the planet, especially alongside other planets and in this kind of scientific context. 


  • Of all the planets in our solar system, Venus and Mars are most like Earth.
  • Scientists and governments met Monday to finalize a major U.N. report on how global warming disrupts people’s lives, their natural environment and the Earth itself, according to USA Today.

Earth (lowercase) is used when referring to dirt or informal contexts such as idioms or with metaphorical usage. 

  • She seems like a down-to-earth kind of person. 
  • He dug up some earth and with it, a few worms.

AP and Chicago differ on whether to capitalize Earth after “the” in scientific contexts, with AP preferring to keep it capitalized and Chicago choosing to lowercase. —Sarah Muench