The most persuasive evidence that Voyager 1 has crossed the termination shock is its measurement of a sudden increase in the strength of the magnetic field carried by the solar wind, combined with an inferred decrease in its speed.

BBC: Voyager impression (Nasa)

The Sun's magnetic field and solar wind - mainly in the form of electrons and protons coming out of the Sun - protects the entire Solar System by acting as a sort of shield from cosmic rays (very energetic particles and radiation from outer space).

BBC: Viewpoint: The Sun and climate change

But since the wind consists of charged particles, it will interact with a magnetic field.

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Changes in the winter wind field broke up floating sea ice to create cracks that suggest the "opening of a Venetian blind, " said Dr Serreze.

BBC: Record ice loss in Arctic

In the ocean, most of the movement of heat and salt, the real Thermohaline Circulation, is driven directly and indirectly by the wind field.

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