It is a vast region extending from about 50 km altitude to geocentric distances in excess of a million km. When CMEs are directed towards the Earth, they cause large magnetic storms that greatly affect the magnetosphere, ionosphere and thermosphere, producing spectacular auroral displays at locations where the aurora is rarely seen. The varying conditions of geospace, including these dramatic storm effects, are referred to as space weather. A daily plot from the radar, showing the location and velocity of ionospheric features over the course of a day Accurate space weather predictions are of increasing economic importance because of the deleterious effects caused by magnetic storms on such devices as communication and Earth resource satellites, and electric power grids. Also, high space winds increase drag on satellites in space, causing them to slow and change orbit.
Auroras are the only sign of space weather visible to the naked eye from Earth.
They are geomagnetic storms in which electrons and ions enter Earth's atmosphere near the poles striking molecules and atoms in the high atmosphere, causing them to glow in different colours. Some aspects of space weather, including magnetic storms, affect much of modern technology. Magnetic storms can disrupt many communications systems which use the ionosphere to reflect radio signals. The same applies to sea and air navigation systems. Knowledge of when storms abate, or are about to start, therefore has commercial implications.