"Sky" and "heaven" has both two different meanings in the Quran.
I will first prove that it means the universe (as in space as we know it) :
"We have indeed decked the lower heaven with beauty (in) the stars" As-Saffat 6
"Lower heaven", but there are no stars in our atmosphere, so the lower heaven means our universe.
"3. He Who created the seven heavens one above another" Al-Mulk 3
Seven heavens one above another, do we have 7 atmospheres one above the other ? No.
So here, heaven means universe.
Now, I will prove that it means our own atmosphere that we breath the air from :
"19. Or (another similitude) is that of a rain-laden cloud from the sky" Al-Baqara 19
Do you usually see any clouds in the universe ? Does rain come from our own sky or from the universe ? It comes from our own atmosphere.
"40. "It may be that my Lord will give me something better than thy garden, and that He will send on thy garden thunderbolts from heaven, making it (but) slippery sand!" Al-Kahf 40
There usually aren't any thunderbolts in the universe. This also proves that sky and heaven can mean our own atmosphere.
"25. The Day the heaven shall be rent asunder with clouds, and angels shall be sent down, descending (in ranks)" Al-Furqaan 25
Again, same thing with clouds.
"48. It is Allah Who sends the Winds, and they raise the Clouds: then does He spread them in the sky as He wills, and break them into fragments, until thou seest rain-drops issue from the midst thereof" Ar-Room 48
He spreads them in the sky, not between Jupiter and Neptune.
So you see, sky and heaven can mean two different things.
It may seem contradictory, but it isn't, nothing contradictory here. I hope you don't try to oppose this, it's God that's talking here, not me.
Two things about the heaven meaning universe : either, it means a part of the entire universe (so one seventh of the entire universe God made) or an entire universe, with 7 universes existing. One other thing : you didn't understand my answer, the atmosphere isn't a universe, so there are only 7 universes or 7 parts of the 1 big universe, not 8.
And no, I didn't say that the Earth was made of the sky as of our own atmosphere, I said literally the opposite.