An Interstellar Climate

The final act of some forgotten star,

Unleashes unseen light at breakneck speed;

And once these cosmic rays have journeyed far,

Into our atmosphere they start to bleed.


This energy from interstellar rays,

Is tempered by the Sun’s magnetic haze;

Creating nuclei from which clouds form,

A dying star can cause our Earth to warm.

An illustrated drawing of atmospheric showers from very high energy cosmic rays (Photo Credit: Simon Swordy and NASA).

This is a Heroic Rispetto, inspired by rec­­ent research which has shown how cosmic rays from supernovae can lead to the creation of clouds on Earth, and in doing so can influence our climate.

Cloud Condensation Nuclei (CCN) are aerosols (minute particles suspended in the atmosphere) that act as the starting points for the condensation of water vapor into clouds. These CCN are extremely small (0.0002 to 0.006 millimetres in diameter), and tend to originate from the soil, the ocean (in the form of sea salt), and through the burning of vegetation and fossil fuels. More CCN mean more clouds and therefore more solar energy reflected back into space, resulting in a colder climate. Similarly, fewer CCN result in fewer clouds and a warmer climate.

This new research has theoretically and experimentally demonstrated how atmospheric ions, produced by the energetic cosmic rays that originate when stars explode during supernovae events, can help the growth and formation of CCN in our atmosphere. These high-energy cosmic rays create ions (positive and negative molecules) in the atmosphere, by knocking electrons out of air molecules. These ions help to accelerate the formation of CCN from aerosols in the atmosphere, and can thus lead to the creation of further clouds, and as such a cooling of the Earth’s climate. The rate of cosmic rays reaching the Earth is also influenced by variations in the Sun’s magnetic field; when it is weaker more cosmic rays are able to reach the Earth and therefore more clouds can form and the atmosphere is cooler. Likewise, at times when the Sun’s magnetic field is stronger, fewer cosmic rays reach the Earth, resulting in fewer clouds, and a warmer climate. This new research explains how the amount of solar energy reaching the surface of the Earth can help explain historical variations in the Earth’s climate (e.g. the Little Ice Age from 1300-1900 AD corresponds to a period of low solar magnetic activity) and also how it can be used to explain future climate changes.


An audio version of the poem can be heard here.

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