magnetosphere

Volume of space, surrounding a planet, in which the planet's magnetic field has a significant influence. The Earth's magnetosphere extends 64,000 km/40,000 mi towards the Sun, but many times this distance on the side away from the Sun. That of Jupiter is much larger, and, if it were visible, would appear from the Earth to have roughly the same extent as the full Moon. The Russian-led space missions Coronas-I (launched in 1994) and Coronas-F (launched in 2001) were designed to investigate the magnetosphere of the Sun.

The Earth's magnetosphere is not symmetrical. The extension away from the Sun is called the magnetotail. The outer edge of the magnetosphere is the magnetopause. Beyond this is a turbulent region, the magnetosheath, where the solar wind is deflected around the magnetosphere. Inside the magnetosphere, atomic particles follow the Earth's lines of magnetic force. The magnetosphere contains the Van Allen radiation belts.