The second day 1:6-8

1:6 The "expanse"refers to the heavenly vault above the earth. Moses called it the "firmament"(AV) or "sky"(NIV). God placed the sun, moon, and stars in it (vv. 16-17).⁶³

1:7 God separated the waters so some of them remained on the earth and some were above the earth in the atmosphere. Before He made this division there may have been a dense fog over the whole surface of the earth.⁶⁴

1:8 "Heaven"is the same as the "expanse."Moses used it here as a general term to describe everything above the earth from man's viewpoint (v. 8).