A perfect sun-storm

A geomagnetic storm on January 17, 2013, provided unique observations that finally resolved a long-standing scientific problem. For decades, scientists had asked how particles hitting Earth’s magnetosphere were lost. A likely mechanism involved certain electromagnetic waves scattering particles into the Earth’s atmosphere. More recently, another mechanism was proposed that caused particles to be lost in interplanetary space. Scientists recently found that both mechanisms play a role affecting particles at different speeds.