The Firework Nebula, known to astronomers as "GK Per", is the result of a type of stellar explosion called a nova. In a nova, a very compact star called a white dwarf blasts away gas that had accumulated on its surface. In this case the nova occurred in the year 1901 and is called Nova Persei 1901. This nova became as bright as one of the brighter stars we see in the night sky, but then faded until only a telescope could see it. Soon astronomers could see an expanding shell of gas that eventually became this spectacular nebula. The unusual "fireworks" type feature of this nebula is still a matter of research and discussion.