Nebulas are magnificently beautiful celestial clouds
composed mostly of hydrogen gas and interstellar dust particles.
Many nebulas throughout the universe exist in galaxies. There are
many types of nebulas; more specifically, four main types. The categories
are Planetary, Diffuse, Supernova Remnants and Dark Nebulas. There
are also nebulas under the category Herbig-Haro. These types are
very bright and small. This effect is due to jets of gas and other
particles which are expelled by a star during its stages of formation.
Planetary Nebulas, as their name suggests, resemble planets. In
actuality, however, these nebulas are the shells of star material
a red giant sheds during its death stages (when it transforms into
a white dwarf star). Since these red giants shed layers, or clouds
of gas and other material, this goes along with the definition of
a nebula. These types of nebulas are very common and it is usually
of no surprise when new ones are spotted.