A new study suggests that the lengthening of the days is related to the oxygenation of the atmosphere. Since its formation in fact, our Planet has reduced its speed gradually lengthening the day
The Earth, since its formation about 4.5 billion years ago, has gradually reduced its rotational speed. The consequence has been a gradual lengthening of the day that has made significant changes over eons. New research suggests that one of these changes is related to the oxygenation of Earth’s atmosphere. The blue-green algae, called cyanobacteria, that emerged 2.4 billion years ago would have been able to produce more oxygen precisely because the days became longer. The study was published in Nature Geoscience and was carried out by microbiologists from the University of Michigan, the Max Planck Institute for Marine Microbiology and the Leibniz Centre for Tropical Marine Research in Germany.
The effects of Earth’s speed on oxygenation
According to the researchers, there are two components to consider: the Earth’s slowing rotation and the major oxidation event on the globe, which is when cyanobacteria emerged. The reason why the Earth is slowing down depends on the gravitational attraction exerted by the Moon that causes a rotational deceleration related to the gradual receding of our satellite. Based on fossil evidence, it was discovered that 1.4 billion years ago the days were only 18 hours long, while about 70 million years ago their duration was half an hour shorter than the current 24 hours. The results therefore suggest that we are gaining 1.8 milliseconds per century.
About cyanobacteria, 2.4 billion years ago they emerged in such large quantities that the Earth’s atmosphere experienced a large and significant increase in oxygen. Without this oxidation, scientists believe that life could not have originated. From observing cyanobacterial microbes in the Middle Island Sinkhole in Lake Huron, which are thought to be analogous to those responsible for the Great Oxidation, microbiologists have linked the length of days to the activity of these organisms.
Purple cyanobacteria that produce oxygen through photosynthesis and white microbes that metabolize sulfur form a microbial mat at the bottom of Lake Huron. At night, the white microbes rise above the cyanobacteria absorb sulfur; during the day, the opposite happens, with the former retreating and the latter rising to produce oxygen. However, geomicrobiologist Judith Klatt of the Max Planck Institute for Marine Microbiology in Germany explained that “it takes a few hours before (the cyanobacteria) really get going.” This means that oxygen is produced in a reduced window of the day. From this observation, oceanographer Brian Arbic of the University of Michigan wondered if the length of days might have affected photosynthesis.
To prove this hypothesis, the team performed experiments and measurements on microbes, both in their natural environment and in a laboratory setting, and performed detailed modeling studies based on their findings to link sunlight to microbial oxygen production and microbial oxygen production to Earth’s history. “The intuition suggests that two 12-hour days should be similar to one 24-hour day,” explained marine scientist Arjun Chennu of the Leibniz Center for Tropical Marine Research in Germany. “But the release of oxygen from bacterial mats is limited by the rate of molecular diffusion.”
Scientists’ measurement results therefore showed that there is a fundamental link between the length of the day and amount of oxygen that can be released by soil-dwelling microbes. The slowing down of the Earth, resulting in longer days, would allow for the production of greater amounts of oxygen in the atmosphere that would prolong the survival of the planet’s animal and plant species.
Regarding the origin of the first life forms on our planet, another research in Canada has discovered sponge fossils that could predate the dating of the appearance of animals on Earth by 350 million years.
Stefania Bernardini