Title: Solar Flare

Source: Skylab

Information: This photograph of the Sun, taken December 19, 1974 by NASA's Skylab 4, shows one of the most spectacular solar flares (upper left) ever recorded, spanning more than 588,000 kilometers (367,000 miles) across the solar surface. A previous picture, taken some 17 hours earlier, showed this feature as a large quiescent prominence on the eastern side of the Sun. The flare gives the distinct impression of a twisted sheet of gas in the process of unwinding itself. Skylab photographs such as these may provide clues to the mechanism by which such quiescent features erupt from the Sun. In this photograph, the solar poles are distinguished by a relative absence of supergranulation network, and a much darker tone than the central portions of the disk. Several active regions are seen on the eastern side of the disk. The photo was taken in the light of ionized helium by the extreme ultraviolet spectroheliograph instrument of the U.S. Naval Research Laboratory.