The rainbow ring in this animation is full of tiny radioactive missiles traveling close to the speed of light, shown in this animation as yellow and blue streaks.
Far above Earth, this high-energy radiation from space can damage satellite electronics and pose serious health risks to astronauts. The particles also constantly charge towards the planet’s surface, but luckily an invisible shield of plasma bent into a doughnut shape by Earth’s magnetic field, shown in green, keeps radiation at bay.
Now John Foster from the Massachusetts Institute of Technology and colleagues have found that there is an absolute limit on how close it can get a comfortable 11,000 kilometres from the surface. A phenomenon called “plasmaspheric hiss” seems to be responsible: very low-frequency electromagnetic waves just inside the boundary of the plasma shield that sound like hissing static when played through a speaker.
“It’s a very unusual, extraordinary, and pronounced phenomenon,” says Foster. “What this tells us is that if you parked a satellite or an orbiting space station with humans just inside this impenetrable barrier, you would expect them to have a much longer lifetime. That’s a good thing to know.”……….
See full story on newscientist.com
Image : NASA’s Scientific Visualization Studio