False-colour extreme ultraviolet image of a giant loop prominence on the Sun, recorded by the Skylab space station on December 19, 1973. The image was recorded at the 30.4 nanometre wavelength of helium atoms stripped of 1 electron; these atoms occur in the lower solar atmosphere & so the image shows the clumpy nature of helium gas just above the Sun's visible surface. The prominence, one of the largest recorded in a decade, erupted from the Sun over about 2 hours. It consists primarily of material at a temperature of 20,000 degrees K, with some strands at about 70,000 K. Ref: A NEW SUN - The Solar Results from Skylab, page 162.