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. And God made the two great lights—the greater light to rule the day and the lesser light to rule the night—and the stars. And God set them in the expanse of the heavens to give light on the earth, to rule over the day and over the night, and to separate the light from the darkness. And God saw that it was good. And there was evening and there was morning, the fourth day.

Genesis 1:14-19 (ESV)

Then God said, “Let bright lights appear in the sky to give light to the earth and to identify the day and the night; they shall bring about the seasons on the earth, and mark the days and years.” And so it was. For God had made two huge lights, the sun and moon, to shine down upon the earth — the larger one, the sun, to preside over the day and the smaller one, the moon, to preside through the night; he had also made the stars. And God set them in the sky to light the earth, and to preside over the day and night, and to divide the light from the darkness. And God was pleased. This all happened on the fourth day.

Genesis 1:14-19 (TLB)

This chronicles a further change of the sky from a translucent atmosphere, where the light from the sun, moon, and stars are weak and diffuse, to a transparent atmosphere, where the light from the sun, moon, and stars can be seen clearly and bring about the seasons and mark the days and years.

This change in the transparency of the cloud cover and atmosphere can be deduced from the oxygen levels of the atmosphere. The major turning point of the level of oxygen in the atmosphere was the Great Oxidation Event, which tool place about 2.4 billion years ago. By this time, oxygen began to accumulate in the atmosphere rather than being dissolved in the oceans.  Atmospheric oxygen likely rose from near zero to roughly 0.1–1% of today’s level. This was still very low compared to modern oxygen levels (21%), but it was a dramatic change for Earth. After the Great Oxidation Event, oxygen levels did not
continue rising quickly. For nearly 1.5 billion years, Earth experienced a long
interval where atmospheric oxygen remained low but stable, probably less than
1% of today’s level. 

 

The rise of oxygen had important effects on how light passed through the atmosphere. Even small amounts of oxygen allowed ozone (O₃) to form in the upper atmosphere. Ozone absorbed harmful UV light, making Earth’s surface safer for life. Higher oxygen reduced methane levels, which likely decreased thick organic hazes that had previously made the sky more opaque and possibly orange-colored. Although oxygen itself does not strongly affect visible light, its indirect effects made Earth’s atmosphere more transparent and stable.

Around 800 millions of years ago, the oxygen level began to rise. By about 400 million years ago, the oxygen may have increased to close to the current levels of oxygen (21%). At this level, we can expect the atmosphere to be transparent enough to clearly see the moon, sun, and stars. 

Probable Time Frame ~340 to ~330 million years ago

  • By about 340 million years ago, oxygen level should approximately match current oxygen levels in atmosphere (~21%)

Videos about Day 4 of Creation

Playlist

3 Videos
YouTube TitleDescription
Early Earth AtmosphereFirst earth atmosphere. Collision, moon, Hadean. Cynobacteria. Banded iron formations.
Evolution of Earth's AtmosphereEvolution of the atmosphere of the earth with chemical composition and the influence of temperature dependent reactions, volcanic activity, and living organisms.
Evolution of the Earth's AtmosphereAnother description of the chemical composition of the atmosphere of the earth and how that changes during earth's evolution.