What is solar wind?

Solar wind streams from the Sun at a blistering 400 kilometres
(250 miles) per second. The intense heat of the corona – the
outermost portion of the Sun’s atmosphere – energises particles
to such a level that the Sun’s gravitational field can no longer hold
on to them and they escape into space. Solar wind strength varies,
creating space weather capable of disrupting technology, like global
positioning system (GPS) satellites.
The movement of solar wind has a characteristic pattern that
resembles a rope wobbling up and down – technically known as an
Alfvén wave (after Hannes Alfvén). These magnetic strings can be
observed as the greenish light that appears during the polar auroras.
Until recently scientists have struggled to understand this unusual
wave behaviour, but a new set of models – based on similar waves
generated by polarised light – might enable us to understand, and even
predict, future fluctuations in solar wind.


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