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"
East of Antares
23/06/2006
st of Antares, dark markings seem to sprawl through the crowded star fields toward the center of our Milky Way Galaxy. Cataloged in the early 20th century by astronomer E. E. Barnard, the obscuring interstellar dust clouds include B72, B77, B78, and B59, seen in silhouette against the starry background. Here, their combined shape suggests smoke rising from a pipe, and so the dark nebula's popular name is the Pipe Nebula. This gorgeous and expansive view was recorded in very dark skies over Hakos, Namibia. It covers a full 10 by 7 degree field in the pronounceable constellation Ophiuchus.