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"
Lynds Dark Nebula 43
30/10/2025
Sure, Halloween is an astronomy holiday. But astronomers always enjoy scanning the heavens for spook-tacular galaxies, stars, and nebulae. This favorite is item number 43 from the Beverly Lynds 1962 Catalog of Dark Nebulae, fondly known as the Cosmic Bat nebula. While its visage looks alarmingly like a scary flying mammal, Lynds Dark Nebula 43 is over 12 light-years across. Glowing with eerie light, stars are forming within the dusty interstellar molecular cloud that is dense enough to appear in silhouette against a luminous background of Milky Way stars. Watch out. This Cosmic Bat nebula is a mere 400 light-years distant toward the serpent-bearing constellation Ophiucus.