It's absolutely impossible. haha It is a kind of Korea idiom.
In Korea, this expression is used to express how hard doing something is.
If you are asked or expected to do something impossible, you can say "Are you kidding? That's impossible! It is like picking up the star in the sky!!
(농담하는거야? 그건 불가능해! 이건 하늘에 별따기나 마찬가지라고!)
"하늘의 별따기(Picking up the star in the sky)"
Hmm... It sounds like a poetic expression isn't it?
As I know, English also has a similar expression.
maybe.... It is like asking(wishing(?)) for the moon in the sky... right?
Would you guys share your country or region's idioms with me!? hahaha