Van Allen Belts
Definition
Two donut-shaped zones of trapped high-energy particles encircling Earth within the magnetosphere.
In plain language
Earth's magnetic field traps radiation in two invisible donuts around the planet. They aren't the aurora's source, but they store storm-injected particles and are why satellite orbits are planned carefully.
The science
The inner belt (protons) and outer belt (electrons) hold particles bouncing and drifting on closed field lines. Storms deplete and re-energize the dynamic outer belt; auroral precipitation involves lower-energy plasma sheet populations.
Why it matters for aurora viewing
Belt behavior tracks the same storms that drive auroras โ "killer electron" enhancements after storms are the satellite operator's aurora aftermath.
See this in action on tonight's data.