"Window-Curtain" Structure of the Orion Nebula Revealed by NASA's Hubble Space Telescope
Recent images made with the Wide Field Camera on NASA's Hubble Space Telescope have revealed the structure of a thin sheet of gas located at the edge of the famous "Great Nebula" in Orion, an estimated 1500 light years from Earth. Astronomers, who compare the appearance of this sheet of gas with that of a rippled window curtain, report that this emission traces the boundary between the hot, diffuse interior of the nebula and an adjacent dense cool cloud. The sheet is seen in light emitted by atoms of gaseous sulfur (shown in red in the photograph). This emission is strongest under conditions which are intermediate between those in the interior of nebula and those in the dense cloud.