Genesis 1:6-8 ESV
6 And God said, “Let there be an expanse in the midst of the waters, and let it separate the waters from the waters.” 7 And God made the expanse and separated the waters that were under the expanse from the waters that were above the expanse. And it was so. 8 And God called the expanse Heaven. And there was evening and there was morning, the second day.

