The Earth’s magnetosphere is the area of influence of its magnetic field.
The magnetosphere refers to the region of magnetic influence of a celestial body. This varies depending on the size of the body and the magnetism it generates. The Earth’s magnetosphere is defined by the region in which the motions of charged particles are largely determined by the influence of the Earth. This effect spans approximately 10 Earth radii (63,731 km or 39,123 mi). Certain bodies known for their magnetism, such as magnetars, a form of pulsar, have magnetospheres that are tens of millions of kilometers across.
Not all astronomical objects have a magnetosphere. All planets in the solar system have it, with the possible exception of Pluto. Icy moons are examples of bodies without a magnetosphere. The magnetosphere is created through electrical currents flowing in space and has nothing to do with ferromagnetic materials.
The magnetosphere repels the Sun’s solar wind, which consists of charged particles, creating a large trail of these particles in space, like a speedboat. The archetypal image of the magnetosphere shows the solar wind being deflected around it.
The magnetosphere was only discovered recently: in 1958 by Explorer I, the second Earth-orbiting satellite ever launched. Its source is a dynamo process that the earth’s core metals are undergoing. We used to know, of course, that the Earth had a magnetic field, but we weren’t sure whether or not it influenced the particles in space. In the same way that magnetic north deviates from true north, the magnetosphere’s orientation is slightly offset from Earth’s rotation.
Unlike Earth itself, the magnetosphere isn’t even spherical in shape. It is deformed by the solar wind. This stellar plasma is resistant to mixing with ions trapped in the Earth’s magnetic field.
The magnetosphere plays an important role in protecting us from some of the energy particles created by cosmic waves. The upper atmosphere intercepts energetic particles and circulates them throughout the magnetosphere. These trapped particles are called the Van Allen radiation belts, or more simply, the Van Allen belts.