The magnetosphere is a region around a planet dominated by the magnetic field created by the planet itself. The geomagnetic field is usually induced by convective currents in the liquid core of a planet or star as explained by the dynamo theory. For example, inside the Earth, the convection currents in the molten outer core creates columns of moving charges due to the Coriolis effect. The induced magnetic field due to the currents is similar to that of a magnetic field generated by a huge bar magnet inside the Earth. The same applies to most of the planets and astronomical bodies. For a planet, the magnetosphere acts as like a shield against the solar winds from the Sun, protecting the atmosphere from being ripped away. The solar winds are the reason why the magnetosphere of a planet like Earth is compressed on the dayside and shaped like a comet's tail on the night side. When enough high-energy particles from the solar winds enter the magnetosphere, they excite and ionize the atoms in the upper atmosphere, emitting light. This astounding and beautiful phenomenon of auroras can be observed in high latitude polar regions on Earth.
Frequently Asked Questionsedit
How does convection in the Earth's core creates a magnetic field?edit
Based on the seismic observations from the surface of the Earth, the inner core of the planet is believed to be made up of a 1200 km thick solid iron, where the temperature and pressure are immense due to gravity. The pressure is higher that it prevents the core from becoming into a liquid. The next layer from the inner core is the outer core, a 2200 km thick layer of molten iron and other metals. Due to the pressure and temperature differences between the inner core and the outer core, thermal convection occurs in this region. Due to the complex motions of the two cores and the Coriolis effect from the Earth's spin, the particles move in a complex manner. The movement creates electric currents, which in turn induces a magnetic field. Due to the nature of the convection cell, the magnetic field induced is sustained.