Supernova cosmic ray particles enters the Earth’s atmosphere and produce shower structures of secondary particles. A phenomenon that according to new research has influenced life on Earth over billions of years. (Illustration: H. Svensmark/DTU Space)

Supernovae and life on Earth appears to be closely connected

Wednesday 19 Jan 22
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Henrik Svensmark
Senior Researcher
DTU Space
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A link between exploding stars, called supernovae, and life on Earth has been discovered, according to new research from DTU.

New research from DTU Space, The Technical University of Denmark, suggest a close connection between the fraction of organic matter buried in sediments on the earth and changes in supernovae occurrence in the universe. This is concluded in a new research article published in the scientific journal Geophysical Research Letters by senior researcher Henrik Svensmark, DTU Space.

"The new evidence points to an interconnection between life on Earth and supernovae"
Henrik Svensmark, senior researcher DTU Space

This correlation is apparent during the last 3.5 billion years and in closer detail over the previous 0.5 billion years. The correlation indicates that supernovae might have set essential conditions under which life on Earth had to exist.

Supernovae might influence Earth's climate

According to Svensmark, an explanation for the observed link between supernovae and life is that supernovae influence Earth's climate.

“A high number of supernovae leads to a cold climate with a significant temperature difference between the equator and polar regions. This results in strong winds and ocean mixing, vital for delivering nutrients to biological systems. High nutrient concentration leads to a larger bioproductivity and a more extensive burial of organic matter in sediments. A warm climate has weaker winds and less mixing of the oceans, diminished supply of nutrients, a smaller bioproductivity, and less burial of organic matter,” explains Henrik Svensmark.

"A consequence is that moving organic matter to sediments is indirectly the source of oxygen. Photosynthesis produces oxygen and sugar from light, water and CO2. However, if organic material is not moved into sediments, oxygen and organic matter become CO2 and water. The burial of organic material prevents this reverse reaction. Therefore, supernovae indirectly control oxygen production, and oxygen is the foundation of all complex life".

According to the new paper, a measure of the concentration of nutrients in the ocean over the last 500 Million years correlates reasonably with the variations in supernovae frequency. The concentration of nutrients in the oceans is found by measuring trace elements in pyrite (FeS2) embedded in black shale, which is sedimented on the seabed.

"The new evidence points to an interconnection between life on Earth and supernovae, mediated by the effect of cosmic rays on clouds and climate," says Henrik Svensmark.

Cosmic rays impact the atmosphere

Previous studies by Svensmark and colleagues have demonstrated that ions help the formation and growth of aerosols, thereby influencing cloud fraction. Since clouds can regulate the solar energy that can reach Earth's surface, the cosmic-ray-cloud link is important for climate explains Svensmark:

"Empirical evidence shows that Earth's climate changes when the intensity of cosmic rays changes. When heavy stars explode, they produce cosmic rays made of elementary particles with enormous energies. Cosmic rays travel to our solar system, and some end their journey by colliding with Earth's atmosphere. Here, they are responsible for ionizing the atmosphere”.