(The physics behind space weather)

In order to protect systems and people that might be at risk from space weather effects, we need to understand the causes of space weather.

The Sun is the main driver of space weather. Sudden ejections of plasma and magnetic field structures from the Sun's atmosphere called coronal mass ejections (CMEs) together with sudden bursts of radiation termed solar flares all cause space weather effects at the Earth. In addition, non-solar sources such as galactic cosmic rays, meteoroids and space debris can all be considered as altering space weather conditions at the Earth.

This section gives a brief description of the main causes of space weather, together with links to further information.

• Solar Activity and the Solar Wind
• The Earth's Magnetosphere: Geomagnetic Storms and Substorms
• Radiation Belts
• Galactic Cosmic Rays, Solar Protons and their entry into the Magnetosphere
• Meteoroids and Space Debris