The space around us has a magnetic structure that we have been able to explore with satellites and slows down the constant bombardment of particles from the solar wind. 

Often, the most significant things go unnoticed. For instance, when was the last time you thought about Earth’s magnetic field? Besides guiding compass needles north and bird migration, it has other everyday impacts. It diverts 1.5 million tons of solar material every second. Without it, our atmosphere would be under constant erosion, unable to deflect solar particles that would strip away our protection. Thus, life as we know it wouldn’t exist without Earth’s magnetic field, which also shields our electronics and DNA from solar bombardment. Like Mercury, Jupiter, Saturn, Neptune, and Uranus, Earth is surrounded by a relatively strong magnetic field, mainly originating from within the planet. This magnetic field, known as a geodynamo, is believed to be fueled by the cooling and crystallization of the core. This process stirs the surrounding liquid iron, creating powerful electric currents that extend the magnetic field into space, forming a protective shield known as the magnetosphere. Around 80 kilometers above ground, a significant fraction of the gas in this region is ionized. Charged particles in this region follow magnetic field lines. moving along specific pathways. The Sun. like all stars. ejects large amounts of high-speed charged particles, known as solar wind. This connection between the magnetosphere and solar wind is at the heart of space weather. If we could visualize Earth’s magnetic field, we would see a dipolar magnetic field, where force lines exit one hemisphere and enter the other. The Earth’s magnetic field is twice as strong at the poles than at the equator. It is also complex and variable, with components like the Van Allen radiation belts, the ring current, the magnetic tail, and the magnetopause. Around the Earth is a region formed by cold, dense plasma that rotates with the Earth. There are also the Van Allen belts, where particles move with relativistic energies. In the ring current, energetic ions move slower but have higher density, producing an electric current that surrounds Earth. This ring current generates a magnetic field opposing Earth’s magnetic field, reducing the field strength measured on the surface when intensified. There are more currents connecting the ring current with the ionosphere, playing a crucial role in auroras and space weather. Understanding the global configuration of particle movement in our space environment requires a key ingredient: the magnetic solar wind. Visualize this interaction by imagining the solar wind as a river’s current and the Earth and its magnetic field as a giant rock. As the solar wind is supersonic, it creates a bow shock and a magnetic tail behind the obstacle. The origin of magnetic storms will be left for another occasion.