As the Sun releases a steady torrent of charged particles in the form of solar wind, Earth's upper atmosphere sheds to protect its lower levels, setting off a powerful cycle of turbulence that leads to problems for orbiting satellites.
"Earth is an active participate in space weather, not just a neutral buoy flopping in the solar wind," said Richard Fisher, division director of NASA's Sun-Earth Connection program at the agency's Washington, D.C. headquarters. "This is a huge change in our thinking."
Opening scientists' eyes to the dynamic and powerful role of Earth in solar storm fallout is a unique satellite, nicknamed IMAGE, equipped with particle detectors, radio sensors and ultraviolet telescopes.
The spacecraft, launched in 2000, has tracked heated particles from Earth's upper atmosphere being ejected into space, then detected some of the particles trapped in Earth's magnetosphere and ultimately into a powerfully charged cloud of plasma that wreaks havoc with radio signals from navigational satellites and other systems.
"We've known that part of the Earth's atmosphere ends up in space ... and it's only there because of this electrical interaction with the solar wind. That's the price the Earth pays for interacting with the Sun and protecting the atmosphere," said Stephen Fuselier, manager of the Lockheed-Martin Advanced Technology Center's Space Physics Laboratory in Palo Alto, Calif.
The particles, however, do not just vanish into space. Some become caught in Earth's magnetic field, becoming 100,000 times more energized in the process, added Donald Mitchell, principal staff physicist with Johns Hopkins Applied Physics Laboratory in Laurel, Md.
"The portions that do return make quite a splash," said Mitchell. "It's really pumped up. When it returns it has certain effects in the lower atmosphere .. it transfers the mid-latitudes into maelstroms."
The particles end up in a cloud of cold gas that envelops the planet, transforming the plasma into a billion-degree whirlpool with fingers reaching down into Earth's ionosphere, where they can affect radio waves carried by navigational and other satellites.
"It's really important to know how and when this can happen," said John Foster, associate director of the Massachusetts Institute of Technology Haystack Observatory.
Before the Imager for Magnetopause to Aurora Global Exploration -- IMAGE's full name -- was deployed, scientists thought most of the charged particles in the plasma pocket came from the Sun itself.
"We have quite a new perspective on space storms," said Fuselier.
The research is expected to be used to create more accurate computer models for space weather predictions.
(Reported by Irene Brown at Cape Canaveral, Fla.)