Cometary globules are isolated, relatively small clouds of gas and dust within the Milky Way.
This example, called CG4, is about 1,300 light years from Earth.
Its head is some 1.5 light-years in diameter, and its tail is about eight light-years long. The dusty cloud contains enough material to make several Sun-sized stars.
CG4 is located in the constellation of Puppis.

The head of the nebula is opaque, but glows because it is illuminated by light from nearby hot stars.
Their energy is gradually destroying the dusty head of the globule, sweeping away the tiny particles which scatter the starlight.
This particular globule shows a faint red glow from electrically charged hydrogen, and it seems about to devour an edge-on spiral galaxy (ESO 257-19 MAG 14) in the upper left.
In reality, this galaxy is more than a hundred million light-years further away, far beyond CG4.
http://www.noao.edu

Imaged with the 16" f3.75 Dream Astrograph.
Apogee Alta U-16M camera.
LRGB image with 60 minutes of Lum
12 minutes for each color (Total of 96 minutes)

Imaged from Tivoli farm in Namibia June 2012.