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
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. 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!
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!
|There are 1
2 3 4 5
6 pages in this feature.
Bibliography | Credits | Feedback | Search