Nebula
A nebula is a giant cloud of gas (mostly hydrogen and helium) and cosmic dust situated between stars in the interstellar medium. Nebulae serve as sites of stellar birth and death—including emission nebulae that glow from ionized gas, reflection nebulae that scatter starlight, and dark nebulae that obscure background stars.
Source: science.nasa.gov
APODs including "Nebula"
The Orion Nebula from Subaru
02/02/1999
The Orion Nebula (M42) shows a host of treasures when viewed in infrared light. Some stars in the Trapezium, an open cluster of stars at the center, are only visible in infrared light. The orange feature above center is called the Kleinman-Low Nebula, and appears greatly affected by newly forming central star IRc2. The blue emission in this representative color photograph is caused by hot gas ionized by the Trapezium stars. This is one of the first photographs ever taken through Japan's new Subaru Telescope.