In verse 3, God begins to create. "Then God said, 'Let there be light'; and there was light." He now cleared away the debris and dust in space and in the atmosphere so that sunlight could penetrate to the earth's surface. An observer on the earth would immediately see the darkness brighten; it would appear that someone had just turned on a giant flashlight. Though the flashlight (the sun) had always been shining, its light could now be seen because God had removed the particles that had blocked it.
Yet, even though the atmosphere was translucent, it was not transparent. Conditions on the earth then were somewhat like those on Venus today. The sun's heat and light could penetrate the atmosphere, but heavy clouds, extending all the way to the earth's surface, enshrouded the planet. Anyone on the surface of the earth would feel as if he were in a thick fog. He could see light, but because of the fog, he would be unable to identify anything. Thus, the sun, moon, and stars were not yet visible.
Earl L. Henn (1934-1997)
Genesis 1: Fact or Fiction?