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"
A Dark Veil in Ophiuchus
29/08/2025
The diffuse hydrogen-alpha glow of emission region Sh2-27 fills this cosmic scene. The field of view spans nearly 3 degrees across the nebula-rich constellation Ophiuchus toward the central Milky Way. A Dark Veil of wispy interstellar dust clouds draped across the foreground is chiefly identified as LDN 234 and LDN 204 from the 1962 Catalog of Dark Nebulae by American astronomer Beverly Lynds. Sh2-27 itself is the large but faint HII region surrounding runaway O-type star Zeta Ophiuchi. Along with the Zeta Oph HII region, LDN 234 and LDN 204 are likely 500 or so light-years away. At that distance, this telescopic frame would be about 25 light-years wide.