The Earth’s magnetic field is very important for humans and other animals on Earth because it protects us from being bombarded (struck) by high-energy charged particles, which are emitted by the Sun.
The stream of charged particles (mainly positively charged protons and negatively charged electrons) coming from the Sun is called the solar wind. When these particles come close to the Earth, they are deflected by the Earth’s magnetic field and cannot shower down to the surface where they can harm living organisms.
Astronauts in space are at risk of being irradiated by solar winds because they are outside the zones where the charged particles are trapped.
The region above the Earth’s atmosphere in which charged particles are deflected by the Earth’s magnetic field is called the magnetosphere.
Relatively often, in addition to the usual solar winds, the Sun may eject a large bubble of material (protons and electrons) with its own magnetic field from its outer atmosphere. Sometimes these bubbles travel towards the Earth where their magnetic fields can join with Earth’s magnetic field.
When this happens, a huge amount of energy is released into the Earth’s magnetosphere causing a geomagnetic storm. These storms cause rapid changes in the Earth’s magnetosphere which in turn may affect electric and magnetic systems on the Earth such as power grids, cell phone networks, and other electronic systems.