Studies in Genesis 1
And God said, “Let there be lights in the expanse of the heavens to separate the day from the night. And let them be for signs and for seasons, and for days and years, and let them be lights in the expanse of the heavens to give light upon the earth.” And it was so. (Genesis 1:14-15 ESV)
When God created the heavens and the earth on the first day He created matter, space and time. Yet, there was no one but Himself who understood the uses of matter, the immenseness of space and the movement of time. Everything began moving at creation and continues moving until creation ceases. Matter moves about space, filling small corners of the universe, leaving immeasurable emptiness between each chunk. Space moves. Light moves. Time moves forward.
God gave creation boundaries which only He may transcend. God set in place the physical laws of the universe which only He may suspend. All of creation in under God’s authority and government.
It is the place of government to set boundaries and implement laws. By doing what He has done God shows is authority and control over His creation. This is not wishful thinking. His laws and boundaries are absolute.
He set each star in place. Our Sun is one of those stars. He determined the heavenly bodies would be signs of the movement of time, for seasons and days and years. And that they were to give light upon the Earth, to separate light from darkness, day from night.
Day is a period of time in which there is light for growth, and heat. Night is a period of subdued but not complete darkness. For the way God created the heavenly lights there is always some light striking the surface of the Earth.