Image: NASA and the IMAGE science team

NASA's IMAGE spacecraft has captured unprecedented views of our planet's magnetic force-field, researchers say, revealing previously invisible intricacies. Findings based on these new images of Earth's magnetosphere, which controls the electrically charged particles in nearby space and shields the planet from the solar wind, appear today in the journal Science.

Of particular interest are several features observed in a doughnut-shaped region on the inside of the magnetosphere called the plasmasphere. Importantly, the images show a tail-like structure predicted some 30 years ago but never confirmed until now. Scientists believe the tail (right) represents a return flow of plasma that results when the solar wind blasts the magnetosphere, distorting it into a raindrop shape. But the new views also reveal unexpected details, including areas in the cloud that are devoid of plasma called troughs, as well as a feature dubbed a "shoulder." Exactly how these troughs and shoulders form remains to be seen.

"People have been investigating the magnetosphere region by in situ measurements on satellites for 30 years," team member Bill Sandel of the University of Arizona remarks. "But they could only get glimpses of the region, sampling here and there. In order to really understand the structure and dynamics of Earth's magnetosphere, you need images encompassing the entire region in a single exposure. That's what we get with IMAGE, and that's why it's unique."

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