Rosette Nebula, named after a little rose, is one of the two major nebulas in the constellation Monoceros (Greek for Unicorn). Monoceris is the east north-eastern neighbor of Orion, and rises directly overhead by evening twilight during March. Rosette nebula is a dimmer, more challenging target to image than many of the nebula in Orion. Orion is full of some of the brightest nebula in the sky. Most of it’s neighbors like Monoceros and Gemini contain much dimmer deep sky objects. Rosette Nebula is an H II region, or a region of low density hydrogen gas, and is part of a giant molecular cloud in Monoceros (similar to the OMCC of Orion). The gas of Rosette emits light directly, rather than reflecting light from nearby stars, and as such is called an emission nebula.
Rosette is accompanied by an open cluster of stars near it’s center, called NGC 2244. The stars of this cluster are particularly intense, primarily large O-type (blue giant) stars that emit light at the highest energy levels. O-type blue giants are as much as 400,000 times brighter than the Sun, and at least 50 times more massive. Blue giants are not the largest stars, however…that crown is worn by red giants, many of which are so large they could swallow every planet in our solar system out to and including Jupiter, reaching nearly far enough to swallow Saturn!
From the periphery of the nebula, dark fingers of cold gas and dust can be seen reaching inwards towards the cluster in the center. These fingers of gas and dust show up dark, as they are too cool to emit light, and instead absorb it. These fine filaments of interstellar matter are what give so many nebula their delicate yet intriguing appearance. At some point in the future I hope to bring more detailed, close up views of some of these regions of nebula like Rosette.