X-ray photograph of the Sun, taken from Skylab, 1970s.
© National Aeronautics & Space Administration / Science & Society
This picture shows a loop in the solar corona colour coded by temperature. These loop-shaped structures are often seen after the eruption of a solar flare, a sudden outburst of energy originating on the Sun's surface and projecting far into its atmosphere. Flares occur near sunspots on boundaries dividing areas with opposite magnetic fields. The loops are thought to be material condensing back out of the corona, the very hot region upper part of the Sun's atmosphere, and returning to the surface. Skylab, America's first space station launched in 1973, carried the Apollo Telescope Mount which contained eight instruments to study the Sun at various wavelengths.