Solar Extreme
Image courtesy NASA
A bright swirl (left of center) on the sun marks the spot where a tumult of plasma sent out the August 1 coronal mass ejection that sparked last week's auroras, as seen in a mosaic picture taken by the Solar Dynamics Observatory. Different colors show regions of temperature variation on the sun.
Solar activity rises and falls on a regular cycle of about 11 years. The last period of peak activity ended in 2001, and it led into a long-lasting quiet spell. (See"Sun Oddly Quiet—Hints at Next 'Little Ice Age'?")
Along with a recent flurry of sunspots, the August eruptions seem to be signs of the star's reawakening—good news for aurora fans, but potential trouble for satellites, astronauts, and some Earthly technologies.
Published August 10, 2010
