Secrets of 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.