Ha detail FCT150 The Rosetta Nebula is a vast cloud of dust and gas, extending over an area of more than 1 degree across, or about 5 times the area covered by the full moon. Within the nebula, open star cluster NGC 2244 is situated, consisted of the young stars which recently formed from the nebula's material, and the brightest of which make the nebula shine by exciting its atoms to emit radiation. Diameter of the nebula of about 130 light years. Discovered by John Flamsteed about 1690.

Source: www.seds.org/messier/xtra/ngc/n2244.htm