Rosette Nebula
The Rosette Nebula (NGC 2237–39, 2244) is a large H II region and stellar nursery about 5,200 light‑years away in the constellation Monoceros. Spanning roughly 100 light‑years, it consists of a central cavity surrounded by ionized gas illuminated and sculpted by the young star cluster NGC 2244, with pillars, cavities, and ongoing star formation.
Source: science.nasa.gov
APODs including "Rosette Nebula"
When Roses Aren't Red
22/02/2018
Not all roses are red of course, but they can still be very pretty. Likewise, the beautiful Rosette Nebula and other star forming regions are often shown in astronomical images with a predominately red hue, in part because the dominant emission in the nebula is from hydrogen atoms. Hydrogen's strongest optical emission line, known as H-alpha, is in the red region of the spectrum, but the beauty of an emission nebula need not be appreciated in red light alone. Other atoms in the nebula are also excited by energetic starlight and produce narrow emission lines as well. In this gorgeous view of the Rosette Nebula, narrowband images are combined to show emission from sulfur atoms in red, hydrogen in blue, and oxygen in green. In fact, the scheme of mapping these narrow atomic emission lines into broader colors is adopted in many Hubble images of stellar nurseries. The image spans about 100 light-years in the constellation Monoceros, at the 3,000 light-year estimated distance of the Rosette Nebula. To make the Rosette red, just follow this link or slide your cursor over the image.