The space shuttle returned to the earth

1.The earth moves round the sun.

2.We live on earth.

3. The space shuttle returned to earth.

I know that the definite article the is used before the word earth when it is considered a planet.

2. When we think of earth as human habitation, we do not use the definite article the.

3.I know that the definite article is not used in idioms such as come down to earth.

But in sentence 3 the space shuttle returned to earth , is earth considered a planet or human habitation? It seems that it is considered human habitation.

I have taken all the sentences from Longman's Active study dictionary. Page number 276.

Is it wrong to say The space shuttle returned to the earth?

Solution 1:

Wikipedia actually addresses this issue:

Originally, earth was written in lowercase, and from early Middle English, its definite sense as "the globe" was expressed as the earth. By Early Modern English, many nouns were capitalized, and the earth became (and often remained) the Earth, particularly when referenced along with other heavenly bodies. More recently, the name is sometimes simply given as Earth, by analogy with the names of the other planets.

I'd say 'sometimes' should be replaced by 'often'. But the use of the article is optional, and almost certainly style-driven (anarthrous Earth being less familiar, homely ... more clinical).

Solution 2:

It's unidiomatic to say The shuttle returned to the earth. Earth is used as a proper noun here, it is the name of a place, it's like saying "The train arrived at Genova" or "We returned to Brussels". No article is needed.

Note that Longman Dictionary capitalises earth in its definition of space shuttle:

"a vehicle that is designed to go into space and return to Earth several times