By Writing styles, Capital letters

I do hope that your teacher didn't give you that question as it gives me serious doubts about their English ability! You can't refer to people as 'it' for a start, and there are lots of other errors. You have a nice natural and fluent writing style. You just need to be a little more careful with...

Your question is not a grammatical one. It's an issue of writing style, and in English, there is no authority (like I'Academie Francaise) to fix writing style. But The Chicago Manual of Style is a kind of authority and it says about the style of celestial bodies as follows:Names of other planets...