Alex Kunkovadded a note 8 years ago

I think that's because the author has made two mistakes. it should be "like the Earth"

In the sentence earth is an abstract term. It means something like a planet to live on

Hola que tal

It should be "Maybe there is a planet somewhere that is like Earth." It is the name of the planet (in this context) so it should be capitalized. There is NO definite article. I can't say why, but it is similar to:
There is no planet like Jupiter.
You would never say:
There is no planet like the Jupiter.

and what about the Moon, then?

strange enough Wikipedia article has it both with and without the definite article
https://en.m.wikipedia.org/wiki/Earth

Іgor, just becase there are moons among which there is the Moon)))

I can't be sure for 100% because I'm not a native speaker, but I guess it's the same like in Russian language with the words Земля like our planet Earth and земля, земли in general meaning like a planet wich can have conditions to have a kind of life on or to be settled on

It sounds right. But true about Igor's remark. *Love you to the moon and back" . *Love you to the end of the world*. Love you until Earth dissapears? Love you until the Earth dissapears? No idea about differences ÷ moon and earth

Thank you, everyone! Thanks a lot!

I guess with the Moon it's the same like with the Earth. They mean the secondary planet of the Earth -> the Moon. If they talk about secondary planets / satellites in general, then it's just moon.
With the world its a bit different because it's not a planet but our surrounding, life ect., so the (this) world. I suppose :-)

Thank you, Irina.

You are welcome but as I said I can't be sure for 100% :-)

I think there's no difference we speak about the Earth as our planet or as a planet in general. In my opinion it must be here the article "the" because the speech goes about our planet "the Earth".

:-) as you wish)))

http://english.stackexchange.com/questions/33282/about-definite-article-before-earth-moon-and-sun
https://www.englishforums.com/English/EarthOrTheEarth/pdcrg/post.htm
https://www.quora.com/English-Grammar-When-Earth-is-referred-as-a-planet-why-do-we-say-the-earth-Shouldnt-it-just-be-Earth
https://forum.wordreference.com/threads/earth-or-the-earth-earth-or-earth.284138/
https://en.m.wikipedia.org/wiki/Earth
This is a never ending discussion :-)
but the verb "must" is too strong to use in your expression Alex

Yeah, you're right. I see) Thanks a lot)

😊👍

And finally, do I think right if I guess it may be correct to say "earth" in the spoken language?

well, it's not like anyone would misunderstand you, if you say that. it's definitely nether Mars, nor Venus. it's something inbetween =)

Actually the rule is simple: when speaking about Earth as a planet (in this case Earth is a proper noun), it should be capitalized and no article should be used. When speaking about the earth as the ground (in this case "the earth" is a common noun), it shouldn't be capitalized and the definite article should be used.