The Rosette Nebula is a large cloud of gas and dust approximately 5,200 light years away, near the Monoceros molecular cloud.
The nebula contains regions of active star formation and spans roughly 130 light years across.
The hot young stars of the central cluster of the nebula (NGC 2244) emit intense radiation in the form of stellar winds, ionizing the gas of the nebula which then re-emits this radiation (creating this 'emission nebula').
As the predominant gas of the nebula is hydrogen gas, the main radiation that is re-emitted from it is at the hydrogen-alpha wavelength (red colour).
This image was created by combining around 7 hours of H-alpha data and 4 hours of colour data I was able to capture last December.