... The Magnetic Sun . ... Galileo had guessed they were clouds floating in the Sun's atmosphere, obscuring some of its light. ... It turned out that the Sun has a polar field somewhat like the Earth's, but that it reverses its polarity during each 11-year cycle. ... Sunspot fields were evidently produced by electric currents, and it was well known that such currents could be generated by a " dynamo process ," by the motion of an electric conductor (e.g. the flow of solar plasma) through a magnetic...
... Files in red?history) . ... Auroral Currents . 25H. Birkeland Currents . ... As noted earlier Kristian Birkeland, reporting in 1903 on his expeditions to the auroral zone, proposed that magnetic disturbances accompanying the aurora were caused by large electric currents flowing down the length of auroral formations. ... In later years these currents became known as the auroral electrojets , and considerable debate ranged over their cause and the way their circuit might be completed. ...
Ice Volcanoes Reshape Europa's Chaotic Surface . Ice-spewing volcanoes and the grinding and tearing of tectonic plates have reshaped the chaotic surface of Jupiter's frozen moon Europa, images from NASA's Galileo spacecraft reveal. ... Although the images do not show currently active ice volcanoes or geysers, they do reveal flows of material on the surface that probably originated from them, said Galileo imaging team member Dr. Ronald Greeley of Arizona State University, Tempe. ... Europa . ...