an entire sky

czemu nie "the entire sky" ?

the entire world
in entire sky
an entire world for him I could give
stars are visible and observable in the entire sky of our planet

mowiac metaforycznie uzywamy an
mowiąc bardziej naukowo używamy the choć pewnie znajdziesz wyjątki, nie ma na to jednej reguły

nie buszuj tyle :D

>czemu nie "the entire sky" ?

a dlaczego nie 'an entire sky'?

>czemu nie "the entire sky" ?

"I can see lots of stars in the sky tonight" is about the sky over my head.
There is only one sky I can see.

Booba, look, there is only one star up there, but it lights up the entire sky.
"The sky," because it lights up the sky over my head—the only one I can see.

Some stars can be so powerful that even one of them can light up an entire sky.
"An entire sky" is not the sky over my head; it's a yardstick against which the star's lighting prowess can be measured.

An evening sky can be a gorgeous dark navy blue.
We reached the camp late. The evening sky was a gorgeous dark navy blue.

'A' and 'an' are sometimes used with SINGULAR NOUNS such as 'sun', 'moon', and 'sky' which refer to just one thing. You normally use 'the' with these nouns, but you use 'a' or 'an' when you are drawing attention to some special feature by adding a modifier or qualifier to the noun. This use is particularly common in literature.

We drove under a gloomy sky.
A weak sun shines on the promenade.

bardziej literackie i metaforyczne podejscie to wlasnie to o czym mowie :D