WRONG.........God created the Earth and Sun on day 2, you can't have a Planet without a Sun to hold it in orbit. Do you know what FIRMAMENT MEANS? Skies, so in verse 7 where God says let the Skies divide the Waters in the Skies {Moisture/Rain} from the Waters BELOW the Skies {Oceans}. So the earth was already in place on DAY TWO, which means the Sun was in place also. The Heavens are the Skies, there are THREE Heavens, our Biosphere Dome, thee Universe Skies and God's Heaven outside our universe.
Gen. 1:6 And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.
7 And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so.
8 And God called the firmament Heaven. And the evening and the morning were the second day.
Sure, we can't calculate how the weather would be without a moon......perhaps you have it wrong. Its not hard to calculate these events.