... NGC4039: Starbirth and Galaxy Death . ... Do star clusters form when galaxies collide? ... A famous star cluster and observatory highlight this picture of Comet Hale-Bopp. ... Massive stars reach a spectacular evolutionary endpoint - supernovae explosions which blast off their outer layers, violently merging stellar material with the gas and dust of the Milky Way. ... Stars form in gas clouds, and the motion of gas clouds tell us about the size and rotation speed of our own Milky Way Galaxy. ...