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The violently hot solar corona is visible in X-radiation. These images from the Yohkoh satellite show how the corona varies with the 11-year solar activity cycle. The bright corona at the left shows high activity, which may be associated with magnetic storms on the Earth and other injurious effects. The dark corona on the right shows the present situation (ca. 1995) of low magnetic activity. The plot at the bottom shows the time variation. Activity will start to increase again in 1997-1998.