It’s common to the point of mootness, but: when describing the planet, Earth is a proper noun and should be capitalized. Otherwise you are referring to soil.
It’s common to the point of mootness, but: when describing the planet, Earth is a proper noun and should be capitalized. Otherwise you are referring to soil.
My dictionary says it’s lower-case. I’ve only ever seen it in lower-case, unless you’re taking about it in the astronomical sense (e.g. “the planet Earth”).