Do the stars tell us anything about the weather?

Dear Tom,
Do the stars tell us anything about the weather?
— Marcella Lipinski
Dear Marcella,
The stars have no direct effect on the weather. But studies in the last few years have indicated the possibility that cosmic rays bombarding the Earth aid in the formation of clouds and consequently they lower temperatures (because increased cloudiness has that effect).
Here is a greatly simplified statement of the process: Cosmic rays, produced by exploding stars, knock electrons out of air molecules, producing ions that aid in the growth of cloud condensation nuclei. This results in increased cloudiness. Variations in the sun’s magnetic activity alter the amount of cosmic rays bombarding the atmosphere. When more cosmic rays reach the atmosphere, there is more cloudiness and a cooler climate; when fewer cosmic rays arrive, the climate is sunnier and consequently warmer.

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