At the inner region of the earth's magnetosphere is the Van Allen Belt. The Van Allen Belt is named after the scientist James Van Allen who discovered it.
The Van Allen belt is one of the radiation layers around the earth that has energetic charged particles racing around. The particles in the radiation belt are believed to come from the solar wind.
The Van Allen belt is dangerous to humans and anyone leaving the planet needs to be protected from them. Even satellites need to be shielded from these particles. If a satellite needs to spend any significant time in the belt all sensitive parts need to be specially protected.