The Fireworks Galaxy (NGC 6946)

The Fireworks Galaxy, NGC 6946, is a spiral galaxy in the constellation Cepheus. It is about 22 million light years away and about 40,000 light years across. It was discovered by German-born British astronomer William Herschel on Sept. 9, 1798, although he assumed it was a gaseous nebula and had no way of knowing it was so distant. Herschel cataloged more than 7,500 nebulae, galaxies, and star clusters. His discoveries include more than 2400 deep-sky objects and the planet Uranus. Herschel's catalog was augmented by discoveries compiled by his sister Caroline and his son John and published as the General Catalog of Nebulae and Clusters in 1864. Its revision to include 7840 deep sky objects, published in 1888 by John Dreyer, was called the New General Catalogue (NGC). The NGC index numbers remain the most commonly used method of labeling astronomical objects.