19:1 glory of God. The “glory of God,” expounded by the heavens, is not only the infinite power, variety and complexity seen in the stars but also the Lord Jesus Christ, “the brightness of His glory” (Hebrews 1:3). The “signs” established in the stars by God (Genesis 1:14) when He arranged the constellations (Job 38:31-33; etc.) originally set forth pictorially the divine plan of redemption through the coming “seed of the woman” (Genesis 3:15).
19:2 sheweth knowledge. The message goes forth through all space (Psalm 19:1) and all time (Psalm 19:2), even though there is no speech or language through which the message is conveyed (the word “where” is not in the original—Psalm 19:3).
19:4 Their line. This refers to the surveyor’s “line,” that is, the physical creation, which is everything in space and time. God’s creation is the standard against which all men are measured. The heavens declare the glory of God, but all come short of the glory of God (Romans 3:23). See also Romans 1:20, which tells us that if men fail to see the Creator through His creation, they are “without excuse.”
19:6 going forth. The Hebrew word does not refer to the sun’s daily orbit, but to that which “goes forth” from the sun itself—that is, the “heat thereof” the radiant energy which sustains all life on earth and even energizes the entire solar system.
19:6 his circuit. The critical charge that this verse reflects an unscientific geocentric view (the sun orbiting a fixed earth) is puerile. All motion is “relative motion,” since no one knows where a stationary “center of the universe” might be (the sun apparently moves in a gigantic circuit around the center of the Milky Way galaxy, and the galaxy itself moves with respect to other galaxies). The most scientific way of dealing with different motions is to assume a point of zero motion, and measure other motions relative to that. The best point to assume as a point of zero motion is the one for which the equations of motion are simplest. For all surveyors, all navigators, and most astronomers, that reference point is the surface of the earth at the location of the observer. David takes this scientific approach in referring to the sun’s motion relative to the earth. At the same time, his statement is also correct for any other assumed fixed point, since the sun and the galaxy do actually move throughout the whole universe.
19:6 hid from the heat. The laws of thermodynamics (i.e., “heat power”) are the most important and universal laws of science, and the sun’s heat “going forth” from its surface provides the basic energy for all earth’s processes. The First Law (conservation of energy in quantity) and Second Law (decay of energy quality) ultimately depend upon the sun’s heat for their meaningful existence and operation.