Supernova Star Explosion Changed Life on Earth

The matter that we, our bodies and our environment are made of comes from the heart of stars, the true matter factory of the Universe (iron, carbon, gold, calcium, oxygen, etc.). This is why it is also poetic — and physically correct — to say that we are stardust. A study has also shown that a supernova close has directly modified our genetic code.

Some stars explode at the end of their lives: the most massive ones whose core literally collapses on itself and those that form a couple, when the smallest (a white dwarf) “steals” matter from its red giant companion. Rest assured, the Sun does not fall into either category; it will die peacefully in 5 billion years.

The final step before the collapse and explosion of massive stars is the synthesis of iron, especially Fe⁶⁰A isotope stable of this element. It is precisely the iron projected into space by the explosions and this Fe⁶⁰ deposited in terrestrial sediments whose age and rate scientists measure to determine their origin. Now there are two important deposits on Earth: 5 million and about 2.5 million years ago.

The Earth is sailing in a void of 1000 light years

Supernovae are not only responsible for the abundance and diversity of elements in the Universe. Their explosion also produces the most powerful radiation there is, called supernovae. gamma. The explosions of gigantic stars (type O) are so colossal that they create radiation cavities in the Galaxy. These two phenomena combined have shaped life and the galactic environment in which we find ourselves: the Earth and the Solar System navigate in a galactic void of 1000 light years, called the local bubble. The authors of the study managed to link the terrestrial deposits of Fe isotopes⁶⁰ to vacuum bubbles and their probable origin. These radiation bubbles would have participated in the evolution of life on Earth…

Come mutate into my galactic bubble!

According to the authors, “It is likely that the Fe peak⁶⁰ about 2.5 million years ago came from a supernova in the Upper Centaurus Lupus association in Scorpio Centaurus (450 light years) or the Tucana Horologium association (220 light years). While the five to six year peak is probably attributed to the entry of the Solar System into the bubble”.

But this local bubble is not a cocoon, it is even a violent place forged by successive supernovae, about 15 over the last 15 million years and nine over the recent six million years. This is a fairly substantial dose of radiation that the researchers have evaluated. This dose seems to them incapable of triggering a mass extinction, but sufficient to cause double strand breaks in DNA and genetic mutations.

Diversification and increase in the number of viruses in Africa, 2.5 million years ago

The authors conclude by explaining that we are unfortunately not yet able to know precisely what impact these doses of radiation had on living things, but that we have, for example, noticed a great diversification of viruses in the African lake of Tanganyika, exactly 2.5 million years ago…