This image is a soft-xray image (3-45 Angstroms) taken by
the Japanese Yohkoh satellite. Yohkoh means "sunbeam" in
Japanese. The satellite is managed by ISAS, the Institute
of Space and Aeronautical Sciences. Yohkoh was designed to
study solar flares and coronal disturbances in the soft
xray band with the goal of better understanding the solar-
terrestrial interaction. 

This particular image is special in that it shows a transit
of Mercury across the sun's disk (view on the right). The
transit track is drawn for reference on the left-hand image.