Heaven in Judaism

Shamayim (שָׁמַיִם), the Hebrew word for "heaven" (literally heavens, plural), denotes one component of the three-part cosmos, the other elements being erets (the earth) and sheol (the underworld). Shamayim is the dwelling place of God and other heavenly beings, erets is the home of the living, and sheol is the realm of the dead, including, in post-Hebrew Bible literature (including the Christian New Testament), the abode of the righteous dead.

The Hebrew word shamayim is constructed of two parts: sham (שָׁמַ) derived from Akkadian samu meaning "sky" or "lofty", and Hebrew mayim (מַיִם) meaning "water". In Genesis 1:6 Elohim separated the "water from the water". The area above the earth was filled by sky-water (sham-mayim) and the earth below was covered by sea-water (yam-mayim). The Hebrew word for the sun is shemesh. It follows the same construction, where "shem" or "sham" (Akkadian: samu) means "sky" and esh (Akkadian: ish) means "fire", i.e. "sky-fire".

The Biblical authors pictured the earth as a flat disk floating in water, with the heavens above and the underworld below. The raqiya (firmament), a solid inverted bowl above the earth, coloured blue by the cosmic ocean, kept the waters above the earth from flooding the world. From about 300 BCE a newer Greek model largely replaced the idea of a three-tiered cosmos; the newer view saw the earth as a sphere at the centre of a set of seven concentric heavens, one for each visible planet plus the sun and moon, with the realm of God in an eighth and highest heaven, but although several Jewish works from this period have multiple heavens, as do some New Testament works, none has exactly the formal Greek system.

...
Wikipedia