Verse 8 covers the naming of the firmament and the indication of time.

And God called the firmament Heaven: for God called see verse 5. This is the first occurrence of the word Heaven since Gen 1.1. The Hebrew word translated Heaven is always plural. It refers here to the place of the stars, sun, and moon (Gen 1.14-16), but it is also the place where birds fly (Gen 1.20). In 1 Kgs 8.30 it is also the place of God, and the place where God is enthroned (Isa 66.1). In English “sky” is not associated with the place of God but is the common term for the open space seen above the earth. Many languages have only one term for sky, “up,” while in others various terms are used according to the location; for example, of high flying birds of prey, of the heavenly bodies, or of the clouds. Examples of naming the firmament are “God gave the name ‘sky’ to the skin that stretches over the earth” and “God named the skin tent that covers the earth ‘sky.’ ”

And there was evening and there was morning, a second day: translators should follow the wording used in Gen 1.5. A second day translates the number term “second.” See comments on Gen 1.5.

Quoted with permission from Reyburn, William D. and Fry, Euan McG. A Handbook on Genesis. (UBS Helps for Translators). New York: UBS, 1997. For this and other handbooks for translators see here .