Four billion years ago, the night sky would have looked very different from what we see today. During this period, the Earth was in its early stages of formation, and the atmosphere and environment were vastly different from what we know today. Here’s what we can speculate the night sky would have looked like:

The first stars were only beginning to form in the universe at this time, so there would not have been many stars visible in the night sky. The universe was much darker than it is today, with the light from distant stars and galaxies still travelling to us over vast distances. The Milky Way galaxy, which our solar system is a part of, would have looked very different, with a less defined spiral structure and a smaller number of stars.

The atmosphere of the early Earth would have been much different than today, with higher concentrations of methane, ammonia, and other gases that could have absorbed and scattered much of the light from the stars. This could have made the night sky appear hazy and less clear than it does today.

The Moon had already formed at this point, and it would have been visible in the night sky. However, the Moon was much closer to the Earth than it is today, appearing up to ten times larger in the sky than it does now.

The positions of the constellations and stars would have been different from what we see today due to the Earth’s precession. Polaris, the North Star, would not have been the guiding star that it is today, as the Earth’s axis pointed towards a different star in the distant past.

The emergence of life on Earth during this period was limited to simple, single-celled organisms, so there would have been no sounds or evidence of human activity that we associate with the night. The night would have been quiet and still, not even the sounds of nature we are accustomed to, such as the rustling of leaves and the chirping of insects would be happening.

In summary, the night sky would have looked very different four billion years ago, with fewer visible stars, a different atmosphere, and a different configuration of the stars and constellations. The emergence of life was limited to simple organisms, so the night would have been quiet and still, with the only sounds coming from weather and geologic activity.

(Written by ChatGPT)