The inner magnetosphere is composed of three populations of charged particles that are trapped in the Earth’s magnetic field. These particles move in circular motions-or gyrate-around the field lines but rarely interact with each other.Ring Current: The ring current is a population of medium-energy particles that drift around the Earth, with protons drifting in one direction and electrons drifting in the opposite direction.Plasmasphere: The plasmasphere is composed of low-energy particles that drift up from the ionosphere, forming a sphere-like reservoir of very cold, fairly dense plasma that co-rotates with the Earth.Van Allen Radiation Belts: The Van Allen Belts consist of high-energy particles that are trapped in two regions. These particles move along the field lines toward the poles until they are reflected back, creating a bouncing movement. Particles with a high enough velocity along the magnetic field will follow the field lines to the poles and enter the upper atmosphere.Ring Current Data: A Coronal Mass Ejection (CME) occurs when magnetic forces overcome pressure and gravity in the solar corona. This lifts a huge mass of solar plasma from the corona and creates a shock wave that accelerates some of the solar wind’s particles to extremely high energies and speeds. This in turn generates radiation in the form of energetic particles.Van Allen Probes: NASA’s Van Allen Probes (formerly known as the Radiation Belt Storm Probes (RBSP)) mission will help scientists better understand the processes in the radiation belts. The technological challenge for RBSP is to withstand the very energetic trapped electrons and ions in the radiation belts that are extremely harmful to spacecraft. The Space Station flies below the Van Allen belts, well inside the protective cover of the Earth’s magnetosphere. Most unmanned spacecraft missions are designed so they pass through these belts relatively quickly.
Credit: NASA/Troy Benesch