When astronauts are looking at the earth from space, they see a blue ball surrounded by oceans and sky. However, this picture was not always. According to new data from scientists, billions of years ago, the oceans of the Earth had a green tint, and this color was closely related to the development of the first organisms on the planet - cyanobacteria.
According to a study published in Nature Ecology and Evolution, the oceans of the Earth were 2.5-4 billion years ago saturated with iron, and the chemical processes that occurred in the waters contributed to the emergence of green light, which, in turn, changed the color of water. The ancient oceans of the Earth did not look the way we see them today. Initially, the atmosphere was saturated with carbon dioxide and oxygen is absent. Hydrothermal springs erupted from the bottom of the ocean were thrown into the water by a bi -valent iron, which interacted with light. The presence of a large amount of divalent iron in the oceans did not allow water to reflect light as it happens today. Without ozone, which filters ultraviolet, and without plants that would change the atmosphere, the oceans became a "mixture" with strange optical properties. The iron that was dissolved in the water absorbed the red and blue wavelengths of light, and the green light remained, giving the oceans a characteristic green hue. With the development of cyanobacteria that began to produce oxygen, the situation has changed. The oxygen resulting from photosynthesis has transformed biconal iron into a lengthy, which then formed particles similar to rust. These particles did not disappear quickly and lingered in the water, thus absorbing the red and blue spectra of light, but passing the green that gave the oceans of this color. Cyanobacteria, which are capable of photosynthesis, began to adapt to this new environment, and with the help of special pigments, such as pikorythrobilin, they were able to use green light to produce energy. Due to these adaptations, cyanobacteria became dominant organisms on Earth at that time.
To confirm this hypothesis, scientists have reproduced the model of the Old Ocean on the basis of underwater experiments and analysis of modern conditions. They also made measurements at a depth of 5.5 meters near the islands of Japan, where there are similar conditions, including the allocation of biconal iron from hydrothermal sources. The results confirmed the dominance of green light at certain depths, which corresponded to the conditions of the ancient oceans. The green light of the ancient oceans has significant consequences not only for understanding the evolution of the Earth, but also for astronomy. Traditionally, astronomers searched on other planets of blue oceans, assuming that this is a sign of water. However, according to new data, planets with oceans rich in iron may not have a blue, but a green tint, which will be easier to see at great distances. This means that the detection of green oceans on other planets can be an important clue about the presence of microbial life.
The green oceans of the Ancient Earth have not only evidence of life processes on the planet, but also open up new opportunities to find extraterrestrial life.
