Earth or the Earth

[1karola]

Hi, I always thought that Earth is the only one and we always should use THE before it but during my study I have found examples without it. May you write me why? Is it a reason for it? 

Examples:

How many people live on planet Earth?

Earth is at risk now more than ever.

[Minoo]

Both forms (with and without the definite article) appear frequently in publications; in some contexts, only one works, in others, both seem to work:

 

'Earth' is the name of our planet. As a name, it cannot have a definite article: (Planet) Earth is further from the sun than (planet) Mars.

 

 'the earth' would suggest that there are other 'earths', and we are referring to the one we live on: The ISS rotates as it circles the earth.

 

 

[1karola]

Thank you Minoo for your answer, I've never heard about it. It is knew for me but very interesting

[Jennysh]

Hi, on one of the exams, there is a sentence I find confusing, "There is so much choice." I am wondering why don't we say "there are so many choices "? Thank you!