I have this impression that British 17th century authors avoided capitalising Earth because it felt disrespectful to their Lord.
The Old Testament is mostly focused on the character of God, there are many stories that illustrate how incredibly powerful, all-knowing, vindictive and almighty God is, so these authors must have asked themselves: “How do we show mankind the power, the awesomeness of God, our Lord and Saviour?” and “How do we show our love, our fear and our worship of Him?” And someone replied: “I know, let's not just limit to capitalising the first letter of “Lord”, let's place the entire word LORD in all capital letters and anything else that is not a name of a person, a country, town, village etc. we'll just leave in lowercase.”
Which meant the first letter of places that had proper names such as heaven, hell and earth were in lowercase because they had to pale into insignificance compared to the name of LORD; however, the authors didn't stop there, they capitalized the names that God and later, Adam, gave to things: Day, Night, Heaven, Earth, Seas, Woman, and Man, thereby creating this wonderful contrast, this sense of wide-eyed awe mixed with submission and veneration.
1 In the beginning God created the heaven and the earth. 2 And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters. 3And God said, Let there be light: and there was light. 4 And God saw the light, that it was good: and God divided the light from the darkness. 5 And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day. […] 8 And God called the firmament Heaven.[…] 10 And God called the dry land Earth; and the gathering together of the waters called he Seas:
8 And the LORD God planted a garden eastward in Eden; and there he put the man whom he had formed. 9 And out of the ground made the LORD God to grow every tree that is pleasant to the sight, and good for food; the tree of life also in the midst of the garden, and the tree of knowledge of good and evil. 10 And a river went out of Eden to water the garden; and from thence it was parted, and became into four heads. 11 The name of the first is Pison: that is it which compasseth the whole land of Havilah, where there is gold; 12 and the gold of that land is good: […]
21 And the LORD God caused a deep sleep to fall upon Adam, and he slept: and he took one of his ribs, and closed up the flesh instead thereof; 22 And the rib, which the LORD God had taken from man, made he a woman, and brought her unto the man. 23 And Adam said, This is now bone of my bones, and flesh of my flesh: she shall be called Woman, because she was taken out of Man.
Do I have anything else that supports my initial impression? Well, yes I do. Before risking my hard-earned Internet points on the line, I searched in Wikipedia and found the following article
Reverential capitalization is the practice of capitalizing words, particularly pronouns, that refer to a deity or divine being, in cases where the words would not otherwise have been capitalized:
and God calleth to the light 'Day,' and to the darkness He hath called 'Night;' and there is an evening, and there is a morning — day one.
— Genesis 1:5, Young's Literal Translation (1862)
In this example, "God" is in capitals because it is, like "Day" or "Night", a noun which is here a proper name, whereas "He" is an example of reverential capitalization, since while proper names are capitalized universally, reverence for any particular divinity—belief therein implied on the part of the author who capitalizes pronouns in reference to such being—is not universal. In short, when pronouns are capitalized which usually are lowercase, this usually implies that the writer personally reveres and regards as a deity the antecedent of that pronoun.
Nouns, which are not proper names, can also be capitalized out of reverence of the entity they refer to. Such examples include "the Lord", "the Father", "the Creator".
As to when the word earth should be capitalized, the following guideline says
- Proper nouns
- Names of celestial bodies: Mars, Saturn, the Milky Way. Do not, however, capitalize earth, moon, sun, except when those names appear in a context in which other (capitalized) celestial bodies are mentioned. "I like it here on earth," but "It is further from Earth to Mars than it is from Mercury to the Sun.
- Names of courses: Economics, Biology 101. (However, we would write: "I'm taking courses in biology and earth science this summer.")
But according to the MLA Style Center
We usually lowercase sun, moon, and earth, but, following The Chicago Manual of Style, when the does not precede the name of the planet, when earth is not part of an idiomatic expression, or when other planets are mentioned, we capitalize earth:
The earth revolves around the sun.
The astronauts landed on the moon.
The space shuttle will return to Earth next year.
The four planets closest to the sun—Mercury, Venus, Earth, and Mars—compose the inner solar system.