📘 Definition
The Van Allen radiation belts are two (sometimes three) zones of energetic charged particles trapped by Earth's magnetic field. The inner belt (1,000–5,000 km) consists primarily of high-energy protons; the outer belt (15,000–25,000 km) contains mainly electrons. These radiation zones pose a significant hazard to satellite electronics and astronaut health. Satellites must either operate below the belts (LEO), between them, or above them (GEO), or use radiation-hardened components. GPS satellites at 20,200 km operate within the outer belt. The belts were discovered by James Van Allen in 1958 using data from Explorer 1.
1,000–5,000 km
Inner Belt
15,000–25,000 km
Outer Belt
Protons (inner), electrons (outer)
Particles
1958 (Explorer 1)
Discovered