What is the Solar Wind?
The solar wind is a continuous stream of charged particles (mainly protons and electrons) and magnetic field that flows from the Sun in all directions. It originates in the corona, where the high temperature and open magnetic field lines allow plasma to escape. The wind fills the heliosphere (the region of space dominated by the Sun) and reaches far beyond the planets.
Speed and Density
The solar wind typically has speeds of about 400–800 km/s in "slow" wind and up to 800 km/s or more in "fast" wind from coronal holes. Density and magnetic field (interplanetary magnetic field, IMF) vary. When the wind is fast and the IMF is oriented southward, it can couple effectively with Earth's magnetosphere and trigger geomagnetic activity and aurora.
Effect on Earth
The solar wind compresses Earth's magnetosphere on the dayside and stretches it on the nightside. High-speed streams and CMEs can cause geomagnetic storms and raise the Kp index. Cosmic Radar shows the daily Kp and space weather events so you can see when solar wind conditions are affecting Earth.
Sources and further reading
- NOAA – Solar wind – Solar wind and geomagnetic effects
- ACE Real-Time Solar Wind – Live solar wind data
- NASA – Magnetosphere – Earth's magnetic shield