one of the most beautiful phenomenom in the universe, are made up of gas
left behind by stars forming or exploding. There are many different
classes of nebula, which are: planetary, supernova remnants, diffuse nebula(which
includes reflecting, emission, and dark nebulas). Small, bright nebulas
are called Herbig Haro and are probably jets of gas coming from forming
Planetary nebulas resemble planets, and are actually left over shell material from forming stars during their giant Red Stage. The shell probably came off before the white dwarf stage of the star. Several planetary nebulas exist in the Milky Way.
Supernova remnants are exactly what they say: supernova nebulas are remnants of a star that exploded. Left over remnants become surrounded by gas, causing a nebula. One of the most famous supernova nebulas is the crab nebula in the star constellation Taurus.
are extremely large, and can be light years in width. They have no
definate shape, and are either light or dark. These stellar bodies
often contain some of the most striking and amazing objects in the galaxy,
and have gases that run in chaotic currents all throughout it.
Dark nebulas are nonilluminous or faintly luminous clouds that have never been seen very clearly. They obscure some of the Milky way, but are too distant for any light(even from stars) to be seen.