Heaven and the Heavens

For the authors of the Hebrew scriptures, "the heavens" are a physical reality. "Hashamayim" is plural in Hebrew, just as "heavens" is plural in English.

The Christian concept of Heaven is an eternal state of complete, perfect, everlasting bliss caused by unblemished union with God. "Heaven" in this sense is not a part of the physical universe at all.

The Heavens

Ps 19:2

οἱ οὐρανοὶ διηγοῦνται δόξαν θεοῦ ποίησιν δὲ χειρῶν αὐτοῦ ἀναγγέλλει τὸ στερέωμα

The heavens declare the glory of God; the firmament proclaims the works of his hands.