Either of two toroidal zones containing high-energy ionized particles trapped in Earth's magnetic field and surrounding the planet, beginning at an altitude of about 800 kilometers (500 miles) and extending tens of thousands of kilometers into space.
Either of the two zones surrounding the Earth in which a thin distribution of atomic particles with very high energies are trapped by Earth's magnetic field. The inner belt lies between about 500 and 6,440 km (310 to 4,000 mi) above Earth's equator and consists mostly of a mix of protons and electrons. The upper belt lies between about 15,000 and 30,000 km (9,300 to 18,600 mi) and consists mostly of protons. Both belts are thickest at the equator and have irregular densities of particles. The outer radiation belt is much larger and the number of particles varies, increasing in the aftermath of solar flares. The polar auroras are caused when some of the charged particles from the outer Van Allen belt hit the upper atmosphere. The Van Allen belt is named after its discoverer, American astrophysicist James Van Allen (1914–2006).
Alternative term for Van Allen radiation belt.
Other Word Forms
Origin of van-allen-belt
- After James Alfred Van Allen (1914–2006), American physicist
From American Heritage Dictionary of the English Language, 5th Edition