Exploding stars 'boost Earth life'

Exploding stars may have had a significant effect on the evolution of life on Earth, a study suggests.

The link emerged after scientists matched the geological record dating back 500 million years with what was happening in space.

They found that whenever the Sun and its planets moved to regions in the Milky Way galaxy where exploding stars – or supernovae – were more common, life on Earth prospered.

During these periods the diversity of living things increased.

The theory is that galactic cosmic rays generated by supernovae can alter the Earth’s climate, making it colder.

This results in a greater variety of habitats between polar and equatorial regions, while existing ecosystems are prevented from becoming too set in their ways.

“The biosphere seems to contain a reflection of the sky, in that the evolution of life mirrors the evolution of the galaxy,” said Professor Henrik Svensmark, from the Technical University of Denmark, who led the study.

The findings are published in the journal Monthly Notices of the Astronomical Society.

Supernovae occur when massive stars reach the end of their lives. The explosions are so powerful they briefly outshine an entire galaxy of normal stars.

Prof. Svensmark pointed out that most geological periods seemed to begin and end with either an upturn or downturn in supernova rate.

He added that supernovae may have been responsible for puzzling brief drops in sea level caused by short-lived glacial periods.