The Van Allen belts are two strips surrounding the Earth composing of radiation trapped by the Earth’s geomagnetic field. They’re doughnut-like (toroidal) in shape and the outer belt extends about 60 000 km above the Earth’s surface. Due to their composition of charged particles they can pose a major hazard to satellites that spend too much time within them by disturbing their electrical components.
The closest the inner Van Allen Belt makes it to Earth is in a region called the South Atlantic Anomaly. Satellites that pass through this region need extra shielding to cope with this, the Hubble does not take pictures when passing through and astronauts have reported seeing phosphenes (lights in your eyes) when in this region. Aside from electrons, protons and various ions, it’s also suspected that the Van Allen belts could contain traces of antimatter
The image above shows simulated Van Allen belts in a 1966 Electric Propulsion laboratory experiment.