Day 4: The sun and moon are created. Before we begin on this, notice that the light from the sun and stars was not necessary for God to create the first three days, for the light of the sun is for his creation. God has His means of being able to see clearly.
Here, the sun, moon and stars help regulate time. If we can agree that God created time on day one, he then created the “measuring sticks” for time in day three. This coincides with the Jewish calendars that begin the day of the week and the New Year in the middle of the week.
“Time began with the creation of light on day one, space for life was provided on days two and three, and time-keeping began in the middle of the week”. 
Regarding the sun, newer textbooks are stating that our sun is not ‘any old star.’ Our sun is the right mass, emits the right colors, is the right distance, has the right orbit and emits the right heat to sustain life. The gravitational pull of our sun and moon stabilize our tides. In addition, our moon stabilizes the tilt of the earth’s axis, which is responsible for our seasons and helps keep proper temperature differences between day and night. No other moon in our solar system is the right size to be able to help its planet in any way. “The Earth’s climate stability is dependent to a large extent on the existence of our moon,” James Kasting, professor of geosciences and meteorology at Pennsylvania State University said. The relation of our moon creating a life-friendly earth lends itself to another notch in our Creator’s post-flood backup plan.
 Donald Gowan, Genesis 1-11: From Eden to Babel (Grand Rapids, MI: William B. Eerdman Publishing Co.), 25.
 Lee Strobel, The Case for a Creator (Grand Rapids, MI: Zondervan), 180