Sun struck



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A giant blob of hot, charged mass is ejected from the sun. Will it fry satellites in space or incinerate transformers on Earth?









A magnetic arcade ("row of arches") created by rapid restructuring of the magnetic field in the sun's corona. These arcades are million-degree plasmas confined in magnetic loops and emitting X-rays. Arcades are a signature of a coronal mass ejection. (Numbers indicate Universal, or "Greenwich," Time.)

Images courtesy of Yohkoh, the Institute of Space and Astronautical Sciences, Japan. A Yohkoh spacecraft was built in Japan with instruments from the U.S. and U.K. Courtesy David McKenzie


More than 10 billion megatons of energy may be released in an hour.Getting connected
Feeling disconnected? Then you should sympathize with magnetic fields, which die out locally when their field lines are disconnected. David McKenzie, a physicist at Montana State University, compares magnetic field lines on the sun to a string hammock. "You've got lines and twine going in all kind of directions. They form a network that can support mass."

Similarly, he says, magnetic field lines in the solar atmosphere can "hold cool material way up high." The resulting filaments, also called prominences, appear for weeks on end as dark webs on the sun's surface.

Sometimes, these filaments suddenly get blasted off into space. This is serious -- before we say why it happens, remember that we're not talking about bottle rockets. A giant red blob speeding away from the sun.The explosion, he says, "is the equivalent of several Mount Everests getting blasted off at 1 million miles an hour." A back-of the-envelope calculation says that more than 10 billion megatons of energy can be released in an hour or less when magnetic reconnection occurs.

That astounding amount of power comes from magnetism. For some reason, those magnetic field lines get snapped, and then reconnect. It's not a phenomenon you're likely to see on Earth (although it does happen in labs and nearby space), which is just as well, considering how much energy can be released!

Brilliant yellow brush-strokes indicate X-rays from arcades corona. Just as a cut hammock string is worthless, a magnetic field line cannot exist unless it is connected. If a field line gets stretched until it breaks, it will almost instantly reconnect with another field line, releasing enormous amounts of energy.

From the sun's point of view -- especially when it's as turbulent as it is now -- reconnection is all in a day's work. For operators of satellites, reconnection may necessitate shutting down delicate systems.

For lovers of the aurora, reconnection is cause for celebration!


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