Quiet Sun lets in cosmic rays

via Astronomy Now and Skymania.

NASA’s Advanced Composition Explorer (ACE) spacecraft has detected the highest flux of cosmic rays coming into the inner solar system in half a century, with fluxes nineteen percent, almost a fifth, higher than the previous high. The finger of suspicion also penetrates deep into the solar system, pointing directly at the Sun.

Cosmic rays are electrons and heavy nuclei released from exploding Supernova that then interact with various magnetic fields and end up travelling at incredible speeds through space. Although we’re hit by a soft rain of cosmic rays every on the surface of the Earth and at all times, we’re protected from enormous showers of the things by two layers of magnetic shielding – our Earth’s magnetosphere and the magnetic field of the Sun.

Being charged particles, cosmic rays that are too slow, or hit at the wrong angle are deflected away by magnetic fields. The solar magnetic field, which is the dominant force in an area known as the heliosphere that extends across the entire solar system, is carried from the solar surface by the plasma of the solar wind. Incoming cosmic rays then have to contend with the magnetic field itself, the particle pressure of the solar wind and the amount of twisting and turning of the magnetic field as it extends from the Sun to the outer reaches.

The quiet Sun has led to a weakening of the solar wind pressure. It has also led to a smoothing out of the magnetic field, creating an easier magnetic path for particles to follow inwards. The field itself is also weaker, preventing fewer incoming particles, leading to the highs recorded.

Nevertheless, we’re in a time of historically low cosmic ray fluxes. Research indicates that there used to be twice as many particles coming in as there are now as recently as a few centuries ago, so no need to worry just yet…


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