Here a young star in the Orion Nebula expels a jet of material into the surrounding gas and dust. The jet, shown here in false color as a red stream, emits light in the wavelength characteristic of ionized sulfur atoms under certain density and temperature conditions. Astronomers believe these conditions result from the impact of the jet as it strikes the surrounding material; this process creates a shock wave, much like the sonic booms that occur when airplanes break the sound barrier on Earth.
