Our planet, the Earth, formed about 4.5 billion years ago. From that moment on, its rotation has gradually slowed down and, as a result, its days have progressively extended. As Science Alert indicates, although this slowdown is not noticeable in human time scales, it is enough to generate significant changes throughout eons (billions of years).
“Our research suggests that the ground of rotation of the Earth – in other words, the duration of its days – could have had an important effect on the pattern and synchronization of terrestrial oxygenation.” Gregory Dick, Microbiogo from the University of Michigan.
One of these changes is perhaps the most significant of all, at least for us: The elongation of the days is linked to the oxygenation of the Earth’s atmosphereaccording to a 2021 study published by Nature Geoscience. The green algae (or cyanobacteria) that emerged and proliferated about 2400 million years ago could have produced more oxygen as a metabolic byproduct due to the elongation of terrestrial days.
“A recurring question in Earth’s sciences has been how the Earth’s atmosphere obtained oxygen And what factors controlled when this oxygenation occurred, “explained the microbiologist Gregory Dick, from the University of Michigan and member member of the research group.
1.8 milliseconds per century
The concrete reason why the rotation of the earth is slowing down is because the moon exerts a gravitational attraction on the planetwhich causes a rotational slowdown, since the moon gradually moves away. We know, thanks to the fossil record, that The days lasted only 18 hours 1,400 million years ago, and half an hour less than today 70 million years ago. The evidence suggests that we are winning 1.8 milliseconds per century.
The second component is what is known as the great oxidation event, When cyanobacteria arose in so large quantities that the Earth’s atmosphere experienced a drastic and significant increase in oxygen. Without this oxidation, scientists believe that life as we know it would not have emerged; Therefore, although cyanobacteria can receive some attention today, we would probably not be here without them.
There is still much that we do not know about this event, including questions as hot as why it happened, when it happened. It was necessary for scientists to work with cyanobacterial microbes connected the points. In the Sumidero of Middle Island, in Lake Huron, there are microbial rugs that are believed to be analogues of cyanobacteria responsible for the large oxidation event.
THE SUN AND THE PHOTOSYNTENSIS
Purple cyanobacteria, which produce oxygen through photosynthesis, and white microbes, which metabolize sulfur, compete in a microbial mat on the bed of the Huron Lake. Over there, At night, white microbes ascend to the surface of the microbial mat and are dedicated to devouring sulfur.
At dawn and when the sun reaches sufficient height, white microbes are removed and purple cyanobacteria ascend to the surface. That is when they can start photosynthesize and produce oxygen. However, they take a few hours to get going, since there is a large lag in the morning. Apparently, cyanobacteria rise later, they are not so early.
This means that the daytime window in which cyanobacteria can pump oxygen is very limitedand it was this fact that caught the attention of the oceanographer Brian Arbic, of the University of Michigan, who wondered if the variation of the duration of the day throughout the history of the earth had influenced photosynthesis.
News reference:
Klatt, J.M., Chennu, A., Arbic, B.K. et al. Possible link between Earth’s rotation rate and oxygenation. Nat. Geosci. 14564–570 (2021). https://doi.org/10.1038/s41561-021-00784-3
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