Simultaneous Observations of Solar Protons Inside and Outside the Magnetosphere

Abstract

Simultaneous observations of low-energy (∼0.5 MeV) protons emitted in a solar flare of 7 July 1966 were made with detectors on board the earth satellites Explorer 33 and Injun IV, located outside and inside the earth's magnetosphere, respectively. We find that such protons have full and essentially immediate access from interplanetary space to the polar caps of the earth.