The Trifid Nebula M20 is a rare combination of an emission and reflection nebula. Hot young stars in the southern part of the Trifid have excited the hydrogen atoms in the surrounding gas, causing them to emit Hα light. In the northern part of the Trifid, in contrast, the stars are not hot enough to excite the gas; the blue glow of the starlight being reflected by a myriad of dust particles is only faintly seen in this Hα exposure. Some dust lanes which are not illuminated by starlight run in front of the emission nebula, forming the famous Trifid lines.
M21, which is a loose star cluster of a few stars, is situated to left and slightly above the Trifid Nebula.
M20 - Trifid Nebula, which this image is part of.
Exposure Data
