Study finds frequent impacts of asteroids decreased oxygen levels on earth

It is widely known that our planet earth has endured bombardments of asteroids quite often in the past millions of years. However, new research published in the journal Nature Geoscience has claimed that earth hosted incoming asteroids more often than previously thought. That led to a delay in its atmospheric evolution. When our planet was at its nascent stage, which was between 2.5 and 4 billion years ago, it was frequently bombarded by asteroids, more often than previously thought. The study says that most of these asteroids measured nearly 10 kilometres on average and disturbed the accumulation of oxygen on earth and its overall atmospheric chemistry.

The study explains that whenever an asteroid hit the earth, a giant vapour plume formed a thin layer of sand-size particles in the atmosphere after the vapourised rock condensed and solidified. The study further revealed that repeated asteroid collisions with rocks larger than 10 kilometres might have caused an oxygen sink and pushed most of the element out of the earth’s atmosphere. Under this research, the scientists have discovered the ancient sand particles from the rocks that often went unnoticed. The origin of oxygen on earth is a result of the Great Oxidation Event (GOE), which cooled the planet and raised oxygen levels after spending millions of years as a burning ball of toxic gases. Initially, gases like nitrogen and carbon dioxide were the main components of the atmosphere, making life impossible on earth, according to the study.

Explaining the obvious, study co-author and Harvard professor Nadja Drabon said, “Free oxygen in the atmosphere is critical for any living being that uses respiration to produce energy. Without the accumulation of oxygen in the atmosphere, we would probably not exist”, as per Space.com.

Significance of the discovery

These new findings are significant as scientists will now be able to pinpoint exactly when this planet started resembling the state it is in today. They reportedly analysed the remnants of ancient asteroids that fell on Earth and found that our planet witnessed an asteroid impact approximately every 15 million years, about ten times higher than the rate previously known.

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