Genesis 1:3-5 ERV
Then God said, “Let there be light!” And light began to shine. He saw the light, and he knew that it was good. Then he separated the light from the darkness. God named the light “day,” and he named the darkness “night.” There was evening, and then there was morning. This was the first day.
Genesis 1:14-19 ERV
Then God said, “Let there be lights in the sky. These lights will separate the days from the nights. They will be used for signs to show when special meetings begin and to show the days and years. They will be in the sky to shine light on the earth.” And it happened. So God made the two large lights. He made the larger light to rule during the day and the smaller light to rule during the night. He also made the stars. God put these lights in the sky to shine on the earth. He put them in the sky to rule over the day and over the night. They separated the light from the darkness. And God saw that this was good. There was evening, and then there was morning. This was the fourth day.
If the sun and the moon weren't created until the fourth day what was that which had been lighting the earth for three days?