Earth's magnetic field acts as a shield that funnels solar particles toward the poles to create auroras.

The Earth's magnetic field is generated by the geodynamo process, which involves the movement of molten iron and nickel in the planet's outer core. This process creates a magnetosphere that extends tens of thousands of kilometers into space. It serves as a vital barrier against the solar wind, a stream of plasma ejected by the Sun at speeds reaching 400 to 800 kilometers per second.When solar particles penetrate the magnetosphere, they travel along magnetic field lines toward the polar regions. In the upper atmosphere, these high-energy electrons collide with oxygen and nitrogen atoms at altitudes between 100 and 300 kilometers. These collisions excite the atoms, which then release photons of light as they return to their ground state.The specific colors of the aurora depend on the gas involved and the altitude of the collision. Oxygen typically produces green light at lower altitudes and red light at very high altitudes, while nitrogen creates blue or purple hues. NASA's THEMIS mission and the European Space Agency's Swarm satellites continue to provide critical data on how these magnetic reconnections and particle accelerations occur in real-time.