Back in Time

Frenzied star making was taking place in the Milky way around 2400 million years ago. This frenzy has been discovered to have had a connection with the formation of life on earth. Bacterial count of the seas  soared at that time. This dismisses the idea that  a warm climate is friendlier than a cold one in supporting formation of life.

Scientists noticed that the biggest fluctuations in productivity coincided with high star formation rates and cool periods in earth's climate. Conversely, with low star formation rates,cosmic rays were less intense and earth's climate was warmer but rate of life formation was less. in all icy epochs, the biosphere experienced exceptionally high productivity.

More cosmic rays give more clouds which leads to a colder climate, less cosmic rays give less clouds and a warmer climate. The carbon -13 signal is a remarkable data series spanning 3.8 billion years and variations in this signal corelate with the reconstructed cosmic ray signal. So the idea is that cosmic rays changed climate and that set the conditions for life.

Star formation is measured by counting the number of stars of a given size and determining their age. This is found to be proportional to the overall star formation rate at that time and therefore, also the number of supernova ( where stars are formed by the collision of existing stars) at that time. This gives way to cosmic ray calculation and the relation is drawn.