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"
M78 Wide Field
21/01/2021
Interstellar dust clouds and glowing nebulae abound in the fertile constellation of Orion. One of the brightest, M78, is centered in this colorful, wide field view, covering an area north of Orion's belt. At a distance of about 1,500 light-years, the bluish reflection nebula is around 5 light-years across. Its tint is due to dust preferentially reflecting the blue light of hot, young stars. Reflection nebula NGC 2071 is just to the left of M78. Flecks of emission from Herbig-Haro objects, energetic jets from stars in the process of formation, stand out against the dark dust lanes. The exposure also brings out the region's fainter, pervasive reddish glow of atomic hydrogen gas.