NGC 2170 is a dusty reflection nebula and stellar nursery that formed about 6 to 10 million years ago, located at the edge of the elliptically shaped, giant star-forming molecular cloud Monoceros, some 2,700 light-years away in the constellation of Monoceros.

NGC 2170 is specifically, the blue nebula in the bottom right quadrant of this image, this region ia approximately 15 light-years across and displays a mix of nebula types. The bluish section are reflection nebulae. The dust particle size in these areas reflects blue light. The reddish areas are emission nebulae, ultraviolet light from nearby stars lights the hydrogen and other gases in the nebula, which then emit light of their own in specific colors. Finally, what looks a bit like black ink spilled across the image are dark absorption nebulae, and are only seen because of the light that they block. In other words, the dark nebula is seen in silhouette.

Copyright: Albert Barr