The ominous, dark shapes haunting the left side of the Sun are coronalholes -- low density regions extending abov the surfacewhere the solar magnetic field opens freely int interplanetary space.Studied extensivel fromspace since the 1960s in ultravioletand x-ray light,coronal holes are known to be the source ofthe high-speed solar wind, atoms and electron which flow outward along the ope magnetic field lines.During periods of low activity coronal holes typically coverregions just above the Sun's poles These coronal holes, however, have just moved into view near the Sun's equator, and particles escaping them have already caused notable aurora here on Earth Coronal holeslike this one may last for a few solar rotationsbefore the magnetic fields shift and change configurations.Shown in false-color, this picture of the Sun on March 9 was made in extreme ultraviolet light by th EITinstrument on board the space-based SOHO observatory.
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