Radiation Belts Surrounding Earth (IMAGE) NASA/Goddard Space Flight Center Caption Recent observations by NASA's twin Van Allen Probes show that particles in the radiation belts surrounding Earth are accelerated by a local kick of energy, helping to explain how these particles reach speeds of 99 percent the speed of light. Credit G. Reeves/M. Henderson Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.