Messier 20, the Trifid Nebula   HOME INDEX BACK NEXT
 

Emission and reflection nebula in Sagittarius

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The 18th 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.

Magnitude 6.3
Apparent Size 28'
Distance (light yrs) 5,200
Right Ascension 18:02.4
Declination -23 02

Image details:  Exposure times of 54 minutes luminance and 18 minutes each of red, green, and blue, taken with an SBIG ST-8300M imager and a 14" Meade LX850 telescope at f/6.

August 2014