Researchers think it could lead to a powerful flare some time in the next day or so. If this explosive event does occur, it will liberate in just a few seconds more energy than mankind has ever used. A comet detected three months ago is ambling toward the inner solar system and could be visible to the naked eye late this year, possibly providing the best comet show since Hale-Bopp in 1997. Tickets to the show should be popular, as the comet threatens to make its apparition a one-time engagement. These images from NASA's Cassini spacecraft provide evidence that the auroras originate in electrical currents that connect Io and Jupiter along magnetic-field lines.
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