Understanding なにかご承知ですか


[Same sentence](https://japanese.stackexchange.com/q/40943/11104), different
question:

> 「ではみなさんは、そういうふうに川だといわれたり、乳の流れたあとだといわれたりしていたこのぼんやりと白いものがほんとうは **なにかご承知ですか**
> 。」  
>  Well everyone, this vague white thing which has been called a river and has
> been called a trail of flowing milk, do you know what it really is ?

Literally I translate:

> xがなにかご承知ですか as  
>  "is there some knowledge of x" ->  
>  "Does anyone know about x".

Is this correct? Is it a common way to ask a question? What other ways could
you ask "does anyone know about x?"?




Xがほんとうはなにかご承知ですか literally translates to "Do you know what X really is?"
Although ご承知ですか may be relatively less uncommon than ご存じですか (honorific "to
know ～"), `Xがなにか` is a very common way to ask questions like this.

Xがなにか here forms an _embedded question_ which can be literally translated as
"what X is". Similarly, Xがだれか means "who X is", Xがいつだったか means "when X was",
and so on. Details are explained in this question: [Usage of か after a
clause?](https://japanese.stackexchange.com/q/13034/5010)




It is a perfectly normal way to elicit a response. my self I would take the
meaning in as "Are you aware of x". We use this question at work all the time
when bugs and system error are found. having said that. I would probably not
use it while speaking with friend. But would use it if I were an old man
telling a story to kids or a narrator of a documentary.

easy alternatives could be

なにか分かりますか？

なんなんでしょう？

なにかご存知ですか？ (a little more on the polite side)

