Milkway stars influenced earth's early life
15 November 2006
by Richard Conan-Davies
The early life on earth is closely linked to the cosmic rays, the atomic bullets that rain down on the Earth from exploded stars most commonly from 2.4 billion years ago. By counting heavy carbon atoms, carbon-13, in sedimentary rocks, the team from the National Danish Space Centre led by Dr. Henrik Svensmark, showed how active life was during ancient times. He discovered that the biggest variations in bacterial life coincided with high star formation rates and cool periods in Earth's climate. Yet, during a billion years when star formation was slow, cosmic rays were less intense and Earth's climate was warmer, the biosphere was almost unchanging in its activity. It is thought that cosmic rays led to an increase in cloud cover which tends to cool the planet by reflecting light back into space. This discovery adds to the importance of considering cosmic rays as influencing of climate changes and variations. |
Cosmic rays increased clouds and cooled the planet changing the life cycles on early earth. image: National Danish Space Centre
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