Rosette Nebula. Optical image of the star cluster NGC 2244 (lower left) at the heart of the Rosette Nebula (NGC 2237-2239). NGC 2244 is a cluster of hot young stars born from contraction of the nebula's gas. Radiation from these stars ionises the surrounding gas, causing it to emit light. This nebula lies around 2600 light years away in the constellation Monoceros. This image was produced by the CFH12K CCD camera on the Canada- France-Hawaii Telescope on Mauna Kea, Hawaii, USA.