The Rosette Nebula . ... Credit Copyright: Robert Gendler Explanation: Would the Rosette Nebula by any other name look as sweet ? ... Inside the nebula lies an open cluster of bright young stars designated NGC 2244 . These stars formed about four million years ago from the nebular material and their stellar winds are clearing a hole in the nebula's center, insulated by a layer of dust and hot gas. Ultraviolet light from the hot cluster stars causes the surrounding nebula to glow. ...