The Rosette Nebula's circular symmetry gives it an appearance similar to that of an opened rose. This nebula, located in Monoceros, is 3,000 light years from Earth and is larger than one degree in the sky. It is estimated to be about 130 light years in diameter. The Rosette Nebula is an emission nebula, meaning that it consists of clouds of high temperature gas. The hydrogen atoms in the cloud are heated when ultraviolet light shines on them, and then in turn they emit radiation as they cool. The stars in the Rosette Nebula form an open cluster, meaning that they are not gravitationally bound and will disperse in a relatively short time. The gas and dust at the core of the nebula have been pushed away from the central stars by radiation pressure and stellar wind, making the center relatively hollow. This process will continue until the nebula dissipates. (Copyright Anglo-Australian Observatory)