Solar Wind

The solar wind is a stream of charged particles, mostly electrons and protons, flowing from the Sun. The faster the solar wind is moving, the likelier you are to see an intense northern lights display. The solar wind speed is measured by the DSCOVR satellite 1.5 million kilometres from the Earth.

The speed of the solar wind varies. The normal steady stream of the constant solar wind is roughly 300 km/s (186 mps), but the fast-moving solar wind, flowing from coronal holes in the solar corona, is usually between 500-800 km/s (300-500 mps). When the wind speed reaches this threshold, geomagnetic storms are very likely to occur. Auroras can then become very bright, colourful and dynamic.

The solar wind causes Earth’s magnetic field to rattle. This rattling is observed by magnetometers like at the Leirvogur Magnetic Observatory. That causes solar wind particles stuck in the magnetosphere to flow along the field lines towards the polar regions of Earth. There, the solar wind particles collide with oxygen and nitrogen atoms and molecules in the upper atmosphere, causing it to glow which gives birth to the Northern lights.