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Solar images at photon energies from 250 eV up to a few kilo-electron-volts from the Japanese X-ray telescope Yohkoh (1991–2001). Left: composite of 49 of the quietest solar periods during the solar minimum in 1996. Right: solar X-ray activity during the last maximum of the 11-year solar cycle. The dashed lines show the part of the solar disk where most activity takes place, indicating a different behaviour between the quiet and active Sun.
Image credit: V Anastassopoulos and M Tsagri/University of Patras.