The Van Allen Radiation Belt, also known as the Van Allen belts or radiation belts, refers to the two doughnut-shaped belts of intense radiation surrounding Earth. These zones of energetic charged particles are held in place by Earth's magnetic field. Other synonyms for the Van Allen Radiation Belt include the inner radiation belt, the outer radiation belt, the magnetosphere, and the radiation zone. The term magnetic belt radiation is also used to describe this phenomenon. These synonyms are often used interchangeably to describe the same intense radiation that poses a hazardous threat to astronauts and satellites orbiting Earth.