Cosmic Rays from Exploding Stars Create Clouds and Heat the Earth

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Spiral galaxy NGC 1084 has hostet several star explosions. S Smartt (Queen's University Belfast)/Brian Campbell/ESA/NASA

Particles from exploding stars can create clouds over Earth, which heat up our planet, scientists have discovered. When charged particles from solar rays and supernovae mingle with aerosols, they make clouds gather in a process never described before.

"Finally we have the last piece of the puzzle explaining how particles from space affects climate on Earth. It gives an understanding of how changes caused by solar activity or by super nova activity can change [the] climate," lead author of the research, Henrik Svensmark, said in a press release.

Aerosols form clouds

Aerosols are mixtures of solid particles and liquid drops suspended in gas. They are used in everything from styling your hair to cooling your fridge. Fog, dust and smoke are all examples of aerosols.

Certain aerosols clump together into clouds like candy floss on a stick. Before now, scientists did not believe that small aerosols could survive long enough to cluster together in this way. They were assumed to disintegrate before they could band together as the core of a cloud.

Svensmark, from the Technical University of Denmark, and colleagues theorized that something called ionization might affect the formation of clouds. Their results were published Tuesday in Nature Communications.

Ionic particles help small aerosols get started

Ions are magnetically-charged particles left over from cosmic rays. Solar flares and exploding stars beam cosmic rays through space, forcing the electrons out of air molecules. Cosmic rays can penetrate the Earth's atmosphere, scattering the charged particles throughout the air.

By blasting manufactured clouds with different amounts of ions, Svensmark and team found that the influx of charged particles makes small aerosols clump together into the condensation which makes up clouds. This means that exploding stars and solar flares could build clouds here over Earth from these small aerosols.

More clouds, more heat

Clouds can insulate Earth, raising temperatures. Daniel Spiess/Flickr

Clouds insulate the planet like a blanket, making everything heat up. The more cosmic rays reach our atmosphere, the more clouds are produced, and the warmer the planet gets. In fact, climate scientists proposed earlier this year that thinning clouds could combat global warming.

Svensmark and team suggest that periodic variations of about two degrees may have been influenced by solar activity. Huge temperature variations of up to 10 degrees might be linked to massive events like the explosions of stars.

Such a dramatic change is unlikely any time soon, as the Earth hardly ever passes close to exploding stars. These events are so rare, that scientists believe the last one occurred almost three million years ago.