German astronomer whose work on star charts during the 1840s contributed to the discovery of the planet Neptune in 1846. He also worked out the path of the comet that bears his name.
Encke was born in Hamburg and studied at the University of Göttingen. He was a professor at the Academy of Sciences in Berlin and director of the Berlin Observatory 1825-65.
The new star charts took nearly 20 years to draw up, compiled from both old and new observations. They were completed 1859 but were soon improved upon by those of Friedrich Argelander.
Encke carried out continuous research on comets and the perturbations of the asteroids. What subsequently became known as Encke's comet had been reported by French astronomer Jean-Louis Pons, but little was known of its behaviour. Encke showed that the comet had an elliptical orbit with a period of just less than four years