What? No Sun!?
And while the earth had no form, in the darkness, God, hovering over, in and around this place said: "let there be light". And there was.
In this world we are used to getting our light from the sun. But it would seem things have not always been this way. The laws of light, it's properties, its speed. do not come from the sun. You might be tempted to think that God didn't really do all that much on the first day - you know, compared to the later days of the week anyway. But He was building the foundation for human life. And I suspect we barely know what He brought into this world on the first day.
But we know that as the day ended, there was light.
Another puzzle: At the end of the day, there was what the Bible calls evening and morning. Does that mean the light disappeared for a period of time? How was the day measured before the sun which was not to come until the 4th day?