'Sky' in the Bible

Now when all the people had been baptized, and Jesus also had been baptized and was praying, the sky opened,

Others, to put Him to the test, asked Him for a sign in the sky.

Vain pretenders! You know how to read the aspect of earth and sky. How is it you cannot read this present time?

But it is easier for earth and sky to pass away than for one smallest detail of the Law to fall to the ground.

but on the day that Lot left Sodom, God rained fire and brimstone from the sky and destroyed them all.

Earth and sky will pass away, but it is certain that my words will not pass away.