Genesis 1:8

1:8 God called the expanse “sky.” ¹  There was evening, and there was morning, a second day.

Genesis 1:15

1:15 and let them serve as lights in the expanse of the sky to give light on the earth.” It was so.

[1:8]  ¹ tn Though the Hebrew word can mean “heaven,” it refers in this context to “the sky.”