Emission and reflection nebula in Sagittarius. The 18^th century astronomer John Herschel named this the Trifid Nebula because the brighter (reddish) portion is divided into three sections by dark lanes.  The reddish portion of this nebula is an emission nebula—glowing ionized hydrogen.  The blue portion is a reflection nebula—it is not glowing on its own but simply reflecting the light of the stars within it.  These colors, which are so distinct in photographs, cannot be seen when observing the Trifid through a telescope.  Both parts of the nebula appear colorless with my 18-inch Dobsonian, and I know of no reports of observers seeing any color in this object.

Image details:  23 images, each 150 seconds at ISO 800, taken with a Canon 400D camera through a Meade 12” telescope at f/10.  Image processing with ImagesPlus and Photoshop.

June 2008