[Grammar] ‘to look up IN the sky’ VS ‘to look up AT the sky’

[northpath]

Which sentence is correct?
1. Look up at the sky - it's clear as a bell
2. Look up in the sky - it's clear as a bell

 

[teechar]

I wouldn't use #2.
You can also say, "Look at the sky."

 

[Skrej]

#2 is acceptable if you're referring to something specific in the sky, but not, as others have already pointed out, if you're just referring to the sky in general.

Look! Up in the sky!
It's a bird.
It's a plane.
It's Superman!