Solar activity. False-colour image of the Sun made in 'soft' X-rays (250-3000 electron Volt energy), showing intense coronal activity. The brightness of the image is proportional to the X-ray intensity. Especially active regions are seen at low latitudes (typically 10-20 degrees north and south of the solar equator). Regions of high X-ray emission are often associated with sunspots, the localised intense magnetic field causing a concentration of the ionised material responsible for X-ray emission. The data for this image were gathered at 19:17UT on 15 September 1991 by the Japanese Yohkoh (Sun-ray") astronomical satellite."