Well, to be pedantic about it, that actually depends on the weather conditions, time, place etc., and the eyesight, color perception, as well as language, of whoever is observing it (or those who unfortunately can nazi) [buh-dum-tsh]

We could say instead, that the sky is the sky (many weirdly seem to think the sky is the limit, but no, I'm prettttty sure, it's the sky)

This adds a lot of confusion, so maybe we should let go of the analogies and just state it directly instead...