Solar wind definition
The solar wind is a plasma, a stream of charged particles (ions and electrons) which are continuously escaping from the Sun into the interplanetary medium.
The particles can escape from the hold of the Sun because the solar corona consists of a very hot plasma of which the temperature exceeds millions of degrees. As a consequence, the plasma particles acquire a significant thermal agitation speed, just like the molecules in boiling liquid acquiring high speeds on microscopic scale.
At a certain altitude above the Sun’s surface, the thermal agitation speed of the electrons gets so high (several thousands of km/s) that they can escape the gravitational attraction of the Sun carrying with them positively charged ions. In this way the solar wind is dispersed into the interplanetary medium.
Earth is protected against the Solar wind particles
The magnetic field of our planet protects us almost completely against the incoming solar wind particles by deflecting them. But there are weak zones in this natural shield. Near the poles of Earth, the funnel-like openings in the magnetic shield (the polar cusps) allow these particles to enter. This results in a visible phenomenon called Aurora.
The solar wind collides head-on with the magnetosphere. The collision zone constitutes the outermost boundary of the magnetosphere. To understand the perturbations of the magnetosphere by the solar wind, we need to know the properties of the solar wind itself.
The solar wind is
- the outermost part of the solar atmosphere
- fast (up to 800 km/s and more) (Solar wind speeds, fast and slow)
It is indeed important to know how much matter and energy can penetrate from the solar wind through that boundary into the magnetosphere.
At times of strong perturbations of the solar wind (during periods of strong solar activity) such transfers of mass and energy can cause magnetic storms, dramatic temporary changes in the structure of the magnetosphere.
The solar wind also affects the other bodies in our Solar System