The Rosette

An open star cluster embroiled in a reflection nebula spanning 55 light-years and most commonly called "The Rosette." The cluster heats the gas within the nebula to nearly 18,000 degrees F, causing it to emit light in a process similar to that of a fluorescent tube. A huge percentage of this light hydrogen-alpha, which is scattered back from its dusty shell and becomes polarized. Also known as NGC 2244.